diff --git a/Classes/Aggregate/AbstractAggregate.php b/Classes/Aggregate/AbstractAggregate.php
index 129ff5e..c1b63c2 100644
--- a/Classes/Aggregate/AbstractAggregate.php
+++ b/Classes/Aggregate/AbstractAggregate.php
@@ -49,9 +49,6 @@ abstract class AbstractAggregate
      */
     protected $typoScriptFilePath = 'Configuration/TypoScript/';
 
-    /**
-     * @param array $maskConfiguration
-     */
     public function __construct(array $maskConfiguration)
     {
         $this->maskConfiguration = $maskConfiguration;
@@ -63,12 +60,12 @@ public function __construct(array $maskConfiguration)
     /**
      * Evaluates the configuration and stores necessary Interface information
      */
-    abstract protected function process();
+    abstract protected function process(): void;
 
     /**
      * Remove hidden content elements from configuration
      */
-    protected function removeHiddenContentElements()
+    protected function removeHiddenContentElements(): void
     {
         if (empty($this->maskConfiguration['tt_content']['elements'])) {
             return;
@@ -85,7 +82,7 @@ static function (array $element) {
     /**
      * Remove core fields from configuration
      */
-    protected function removeCoreFields()
+    protected function removeCoreFields(): void
     {
         foreach ($this->maskConfiguration as $table => $configuration) {
             if (empty($configuration['tca'])) {
@@ -100,11 +97,7 @@ static function ($field) {
         }
     }
 
-    /**
-     * @param string $string
-     * @return string
-     */
-    protected function escapeMaskExtensionKey($string)
+    protected function escapeMaskExtensionKey(string $string): string
     {
         return preg_replace('/(m)ask/i', '${\\1ask}', $string);
     }
diff --git a/Classes/Aggregate/AbstractInlineContentAggregate.php b/Classes/Aggregate/AbstractInlineContentAggregate.php
index 7e6ce92..04bafd2 100644
--- a/Classes/Aggregate/AbstractInlineContentAggregate.php
+++ b/Classes/Aggregate/AbstractInlineContentAggregate.php
@@ -19,10 +19,7 @@
 
 abstract class AbstractInlineContentAggregate extends AbstractAggregate
 {
-    /**
-     * @return array
-     */
-    protected function getAvailableInlineFields()
+    protected function getAvailableInlineFields(): array
     {
         $inlineFields = [];
         foreach ($this->maskConfiguration as $table => $configuration) {
diff --git a/Classes/Aggregate/AbstractOverridesAggregate.php b/Classes/Aggregate/AbstractOverridesAggregate.php
index 14014f2..393b48a 100644
--- a/Classes/Aggregate/AbstractOverridesAggregate.php
+++ b/Classes/Aggregate/AbstractOverridesAggregate.php
@@ -30,10 +30,7 @@ abstract class AbstractOverridesAggregate extends AbstractAggregate implements L
      */
     protected $tcaOverridesFilePath = 'Configuration/TCA/Overrides/';
 
-    /**
-     * @param array $tableConfiguration
-     */
-    protected function addTableColumns(array $tableConfiguration)
+    protected function addTableColumns(array $tableConfiguration): void
     {
         if (empty($tableConfiguration['columns']) || empty($this->maskConfiguration[$this->table]['tca'])) {
             return;
diff --git a/Classes/Aggregate/AggregateCollection.php b/Classes/Aggregate/AggregateCollection.php
index f364066..81c03e1 100644
--- a/Classes/Aggregate/AggregateCollection.php
+++ b/Classes/Aggregate/AggregateCollection.php
@@ -36,10 +36,6 @@ class AggregateCollection
      */
     protected $maskConfiguration;
 
-    /**
-     * @param array $aggregateClassNames
-     * @param array $maskConfiguration
-     */
     public function __construct(array $aggregateClassNames, array $maskConfiguration)
     {
         $this->aggregateClassNames = $aggregateClassNames;
@@ -49,7 +45,7 @@ public function __construct(array $aggregateClassNames, array $maskConfiguration
     /**
      * @return AbstractAggregate[]
      */
-    public function getCollection()
+    public function getCollection(): array
     {
         if (null === $this->collection) {
             $this->initializeCollection();
@@ -61,7 +57,7 @@ public function getCollection()
     /**
      * Initializes aggregate objects
      */
-    protected function initializeCollection()
+    protected function initializeCollection(): void
     {
         $this->collection = [];
         foreach ($this->aggregateClassNames as $className) {
diff --git a/Classes/Aggregate/BackendPreviewAggregate.php b/Classes/Aggregate/BackendPreviewAggregate.php
index 90992e2..b2d7560 100644
--- a/Classes/Aggregate/BackendPreviewAggregate.php
+++ b/Classes/Aggregate/BackendPreviewAggregate.php
@@ -40,10 +40,6 @@ class BackendPreviewAggregate extends AbstractOverridesAggregate implements Plai
      */
     protected $templatesFilePath = 'Resources/Private/Backend/Templates/';
 
-    /**
-     * @param array $maskConfiguration
-     * @param BackendFluidCodeGenerator $fluidCodeGenerator
-     */
     public function __construct(array $maskConfiguration, BackendFluidCodeGenerator $fluidCodeGenerator = null)
     {
         $this->fluidCodeGenerator = (null !== $fluidCodeGenerator) ? $fluidCodeGenerator : GeneralUtility::makeInstance(BackendFluidCodeGenerator::class);
@@ -54,7 +50,7 @@ public function __construct(array $maskConfiguration, BackendFluidCodeGenerator
     /**
      * Adds PHP and Fluid files
      */
-    protected function process()
+    protected function process(): void
     {
         if (empty($this->maskConfiguration[$this->table]['elements'])) {
             return;
@@ -66,7 +62,7 @@ protected function process()
         $this->addFluidTemplates();
     }
 
-    protected function addPageTsConfiguration()
+    protected function addPageTsConfiguration(): void
     {
         $rootPaths = $this->getFluidRootPaths();
 
@@ -96,7 +92,7 @@ protected function addPageTsConfiguration()
     /**
      * This adds the PHP file with the hook to render own element template
      */
-    protected function addDrawItemHook()
+    protected function addDrawItemHook(): void
     {
         $this->appendPhpFile(
             'ext_localconf.php',
@@ -266,7 +262,7 @@ protected function getProcessedData(array \$databaseRow, array \$processedTcaCol
     /**
      * Ensure proper labels in $GLOBALS['TCA'] configuration
      */
-    protected function replaceTableLabels()
+    protected function replaceTableLabels(): void
     {
         foreach ($this->maskConfiguration as $table => $_) {
             if (!isset($GLOBALS['TCA'][$table]) || empty($GLOBALS['TCA'][$table]['columns'])) {
@@ -297,7 +293,7 @@ protected function replaceTableLabels()
         }
     }
 
-    protected function addFluidTemplates()
+    protected function addFluidTemplates(): void
     {
         foreach ($this->maskConfiguration[$this->table]['elements'] as $key => $element) {
             $templateKey = GeneralUtility::underscoredToUpperCamelCase($key);
@@ -325,7 +321,7 @@ protected function addFluidTemplates()
         }
     }
 
-    protected function getFluidRootPaths()
+    protected function getFluidRootPaths(): array
     {
         $rootPath = dirname($this->templatesFilePath);
 
diff --git a/Classes/Aggregate/ContentElementIconAggregate.php b/Classes/Aggregate/ContentElementIconAggregate.php
index a4cd594..8d4de4d 100644
--- a/Classes/Aggregate/ContentElementIconAggregate.php
+++ b/Classes/Aggregate/ContentElementIconAggregate.php
@@ -35,7 +35,7 @@ class ContentElementIconAggregate extends TtContentOverridesAggregate implements
     /**
      * Adds content elements to the newContentElementWizard
      */
-    protected function process()
+    protected function process(): void
     {
         if (empty($this->maskConfiguration['tt_content']['elements'])) {
             return;
diff --git a/Classes/Aggregate/ContentRenderingAggregate.php b/Classes/Aggregate/ContentRenderingAggregate.php
index 8221ef5..b15aebc 100644
--- a/Classes/Aggregate/ContentRenderingAggregate.php
+++ b/Classes/Aggregate/ContentRenderingAggregate.php
@@ -55,10 +55,6 @@ class ContentRenderingAggregate extends AbstractOverridesAggregate implements Pl
      */
     protected $partialPath = 'Partials/';
 
-    /**
-     * @param array $maskConfiguration
-     * @param HtmlCodeGenerator $htmlCodeGenerator
-     */
     public function __construct(array $maskConfiguration, HtmlCodeGenerator $htmlCodeGenerator = null)
     {
         $this->htmlCodeGenerator = (null !== $htmlCodeGenerator) ? $htmlCodeGenerator : GeneralUtility::makeInstance(HtmlCodeGenerator::class);
@@ -69,7 +65,7 @@ public function __construct(array $maskConfiguration, HtmlCodeGenerator $htmlCod
     /**
      * Adds TypoScript and Fluid information
      */
-    protected function process()
+    protected function process(): void
     {
         if (empty($this->maskConfiguration[$this->table]['elements'])) {
             return;
@@ -113,10 +109,7 @@ protected function process()
         }
     }
 
-    /**
-     * @param array $element
-     */
-    protected function addTypoScript(array $element)
+    protected function addTypoScript(array $element): void
     {
         $resourcesPath = 'EXT:mask/' . $this->resourcePath;
         $layoutsPath = $resourcesPath . $this->layoutPath;
@@ -157,12 +150,7 @@ protected function addTypoScript(array $element)
         );
     }
 
-    /**
-     * @param string $table
-     * @param array $fields
-     * @return string
-     */
-    protected function addDataProcessing($table, array $fields)
+    protected function addDataProcessing(string $table, array $fields): string
     {
         $dataProcessing = '';
         $index = 10;
@@ -206,13 +194,7 @@ protected function addDataProcessing($table, array $fields)
         return $dataProcessing;
     }
 
-    /**
-     * @param string $table
-     * @param string $columnName
-     * @param int $index
-     * @return string
-     */
-    protected function addFileProcessorForField($table, $columnName, $index)
+    protected function addFileProcessorForField(string $table, string $columnName, int $index): string
     {
         return <<<EOS
     dataProcessing.{$index} = TYPO3\CMS\Frontend\DataProcessing\FilesProcessor
@@ -228,13 +210,7 @@ protected function addFileProcessorForField($table, $columnName, $index)
 EOS;
     }
 
-    /**
-     * @param string $table
-     * @param string $columnName
-     * @param int $index
-     * @return string
-     */
-    protected function addDatabaseQueryProcessorForField($table, $columnName, $index)
+    protected function addDatabaseQueryProcessorForField(string $table, string $columnName, int $index): string
     {
         $where = $GLOBALS['TCA'][$table]['columns'][$columnName]['config']['foreign_field'] . '=###uid### AND deleted=0 AND hidden=0';
         $markerArray = [
@@ -307,10 +283,7 @@ static function ($key, $value) {
 EOS;
     }
 
-    /**
-     * @param array $element
-     */
-    protected function addFluidTemplate(array $element)
+    protected function addFluidTemplate(array $element): void
     {
         $key = $element['key'];
         $templateSubFolder = 'tt_content' === $this->table ? 'Content' : GeneralUtility::underscoredToUpperCamelCase($this->table);
diff --git a/Classes/Aggregate/ExtensionConfigurationAggregate.php b/Classes/Aggregate/ExtensionConfigurationAggregate.php
index c1696cc..8f312a8 100644
--- a/Classes/Aggregate/ExtensionConfigurationAggregate.php
+++ b/Classes/Aggregate/ExtensionConfigurationAggregate.php
@@ -31,8 +31,6 @@ class ExtensionConfigurationAggregate extends AbstractAggregate implements PhpAw
 
     /**
      * Own constructor method to ensure that the mask configuration is not changed before export.
-     *
-     * @param array $maskConfiguration
      */
     public function __construct(array $maskConfiguration, Typo3Version $typo3Version = null)
     {
@@ -44,7 +42,7 @@ public function __construct(array $maskConfiguration, Typo3Version $typo3Version
     /**
      * Adds typical extension files
      */
-    protected function process()
+    protected function process(): void
     {
         $this->addExtEmconf();
         $this->addComposerJson();
@@ -55,7 +53,7 @@ protected function process()
     /**
      * Adds ext_emconf.php file
      */
-    protected function addExtEmconf()
+    protected function addExtEmconf(): void
     {
         $emConfUtility = GeneralUtility::makeInstance(EmConfUtility::class);
         $extensionData = [
@@ -94,7 +92,7 @@ protected function addExtEmconf()
     /**
      * Adds composer.json file
      */
-    protected function addComposerJson()
+    protected function addComposerJson(): void
     {
         $composerData = [
             'name' => 'mask/mask',
@@ -132,7 +130,7 @@ protected function addComposerJson()
     /**
      * Adds ext_icon.png from mask_export extension
      */
-    protected function addExtIcon()
+    protected function addExtIcon(): void
     {
         $this->addPlainTextFile(
             'ext_icon.png',
@@ -147,7 +145,7 @@ protected function addExtIcon()
     /**
      * Adds mask.json configuration file
      */
-    protected function addMaskConfiguration()
+    protected function addMaskConfiguration(): void
     {
         $content = json_encode($this->maskConfiguration, JSON_PRETTY_PRINT);
         $this->addPlainTextFile(
diff --git a/Classes/Aggregate/InlineContentCTypeAggregate.php b/Classes/Aggregate/InlineContentCTypeAggregate.php
index 2e57cc4..be5ff51 100644
--- a/Classes/Aggregate/InlineContentCTypeAggregate.php
+++ b/Classes/Aggregate/InlineContentCTypeAggregate.php
@@ -26,7 +26,7 @@ class InlineContentCTypeAggregate extends AbstractInlineContentAggregate impleme
     /**
      * Adds dataProvider for inline content CType restriction
      */
-    protected function process()
+    protected function process(): void
     {
         $inlineFields = $this->getAvailableInlineFields();
         if (empty($inlineFields)) {
diff --git a/Classes/Aggregate/InlineContentColPosAggregate.php b/Classes/Aggregate/InlineContentColPosAggregate.php
index ee605dd..d2f2951 100644
--- a/Classes/Aggregate/InlineContentColPosAggregate.php
+++ b/Classes/Aggregate/InlineContentColPosAggregate.php
@@ -32,7 +32,7 @@ class InlineContentColPosAggregate extends AbstractInlineContentAggregate implem
     /**
      * Adds dataProvider for inline content colPos name
      */
-    protected function process()
+    protected function process(): void
     {
         $inlineFields = $this->getAvailableInlineFields();
         if (empty($inlineFields)) {
diff --git a/Classes/Aggregate/LanguageAwareInterface.php b/Classes/Aggregate/LanguageAwareInterface.php
index c7804a6..8c1bf41 100644
--- a/Classes/Aggregate/LanguageAwareInterface.php
+++ b/Classes/Aggregate/LanguageAwareInterface.php
@@ -19,8 +19,5 @@
 
 interface LanguageAwareInterface
 {
-    /**
-     * @return array
-     */
-    public function getLabels();
+    public function getLabels(): array;
 }
diff --git a/Classes/Aggregate/LanguageAwareTrait.php b/Classes/Aggregate/LanguageAwareTrait.php
index 603939b..0aa5de1 100644
--- a/Classes/Aggregate/LanguageAwareTrait.php
+++ b/Classes/Aggregate/LanguageAwareTrait.php
@@ -24,10 +24,7 @@ trait LanguageAwareTrait
      */
     protected $labels = [];
 
-    /**
-     * @return array
-     */
-    public function getLabels()
+    public function getLabels(): array
     {
         return $this->labels;
     }
diff --git a/Classes/Aggregate/NewContentElementWizardAggregate.php b/Classes/Aggregate/NewContentElementWizardAggregate.php
index ec7f089..2b6fef6 100644
--- a/Classes/Aggregate/NewContentElementWizardAggregate.php
+++ b/Classes/Aggregate/NewContentElementWizardAggregate.php
@@ -36,7 +36,7 @@ class NewContentElementWizardAggregate extends AbstractAggregate implements Lang
     /**
      * Adds content elements to the newContentElementWizard
      */
-    protected function process()
+    protected function process(): void
     {
         if (empty($this->maskConfiguration['tt_content']['elements'])) {
             return;
@@ -82,10 +82,7 @@ protected function process()
         );
     }
 
-    /**
-     * @param array $element
-     */
-    protected function processElement(array $element)
+    protected function processElement(array $element): void
     {
         $key = $element['key'];
         $iconIdentifier = 'tx_mask_' . $key;
diff --git a/Classes/Aggregate/PhpAwareInterface.php b/Classes/Aggregate/PhpAwareInterface.php
index dbfee7b..3f73e07 100644
--- a/Classes/Aggregate/PhpAwareInterface.php
+++ b/Classes/Aggregate/PhpAwareInterface.php
@@ -19,11 +19,8 @@
 
 interface PhpAwareInterface
 {
-    const PHPFILE_DEFINED_TYPO3_MODE = 1;
-    const PHPFILE_CLOSURE_FUNCTION = 2;
+    public const PHPFILE_DEFINED_TYPO3_MODE = 1;
+    public const PHPFILE_CLOSURE_FUNCTION = 2;
 
-    /**
-     * @return array
-     */
-    public function getPhpFiles();
+    public function getPhpFiles(): array;
 }
diff --git a/Classes/Aggregate/PhpAwareTrait.php b/Classes/Aggregate/PhpAwareTrait.php
index 14187af..55cb443 100644
--- a/Classes/Aggregate/PhpAwareTrait.php
+++ b/Classes/Aggregate/PhpAwareTrait.php
@@ -24,20 +24,12 @@ trait PhpAwareTrait
      */
     protected $phpFiles = [];
 
-    /**
-     * @return array
-     */
-    public function getPhpFiles()
+    public function getPhpFiles(): array
     {
         return $this->phpFiles;
     }
 
-    /**
-     * @param string $fileIdentifier
-     * @param string $content
-     * @param int $flags
-     */
-    protected function addPhpFile($fileIdentifier, $content, $flags = 0)
+    protected function addPhpFile(string $fileIdentifier, string $content, int $flags = 0): void
     {
         $this->phpFiles[$fileIdentifier] = [
             'content' => $content,
@@ -45,12 +37,7 @@ protected function addPhpFile($fileIdentifier, $content, $flags = 0)
         ];
     }
 
-    /**
-     * @param string $fileIdentifier
-     * @param string $content
-     * @param array $flags
-     */
-    protected function appendPhpFile($fileIdentifier, $content, $flags = 0)
+    protected function appendPhpFile(string $fileIdentifier, string $content, int $flags = 0): void
     {
         if (!isset($this->phpFiles[$fileIdentifier])) {
             $this->phpFiles[$fileIdentifier] = [
diff --git a/Classes/Aggregate/PlainTextFileAwareInterface.php b/Classes/Aggregate/PlainTextFileAwareInterface.php
index f107f00..1bb10eb 100644
--- a/Classes/Aggregate/PlainTextFileAwareInterface.php
+++ b/Classes/Aggregate/PlainTextFileAwareInterface.php
@@ -19,8 +19,5 @@
 
 interface PlainTextFileAwareInterface
 {
-    /**
-     * @return array
-     */
-    public function getPlainTextFiles();
+    public function getPlainTextFiles(): array;
 }
diff --git a/Classes/Aggregate/PlainTextFileAwareTrait.php b/Classes/Aggregate/PlainTextFileAwareTrait.php
index e671862..9d5fd06 100644
--- a/Classes/Aggregate/PlainTextFileAwareTrait.php
+++ b/Classes/Aggregate/PlainTextFileAwareTrait.php
@@ -24,28 +24,17 @@ trait PlainTextFileAwareTrait
      */
     protected $plainTextFiles = [];
 
-    /**
-     * @return array
-     */
-    public function getPlainTextFiles()
+    public function getPlainTextFiles(): array
     {
         return $this->plainTextFiles;
     }
 
-    /**
-     * @param string $fileIdentifier
-     * @param string $content
-     */
-    protected function addPlainTextFile($fileIdentifier, $content)
+    protected function addPlainTextFile(string $fileIdentifier, string $content): void
     {
         $this->plainTextFiles[$fileIdentifier] = $content;
     }
 
-    /**
-     * @param string $fileIdentifier
-     * @param string $content
-     */
-    protected function appendPlainTextFile($fileIdentifier, $content)
+    protected function appendPlainTextFile(string $fileIdentifier, string $content): void
     {
         if (!isset($this->plainTextFiles[$fileIdentifier])) {
             $this->plainTextFiles[$fileIdentifier] = '';
diff --git a/Classes/Aggregate/SqlAwareInterface.php b/Classes/Aggregate/SqlAwareInterface.php
index 69744a2..fe16317 100644
--- a/Classes/Aggregate/SqlAwareInterface.php
+++ b/Classes/Aggregate/SqlAwareInterface.php
@@ -19,8 +19,5 @@
 
 interface SqlAwareInterface
 {
-    /**
-     * @return array
-     */
-    public function getSqlDefinitions();
+    public function getSqlDefinitions(): array;
 }
diff --git a/Classes/Aggregate/SqlAwareTrait.php b/Classes/Aggregate/SqlAwareTrait.php
index ccc66ad..e2f0103 100644
--- a/Classes/Aggregate/SqlAwareTrait.php
+++ b/Classes/Aggregate/SqlAwareTrait.php
@@ -24,20 +24,12 @@ trait SqlAwareTrait
      */
     protected $sqlDefinitions = [];
 
-    /**
-     * @return array
-     */
-    public function getSqlDefinitions()
+    public function getSqlDefinitions(): array
     {
         return $this->sqlDefinitions;
     }
 
-    /**
-     * @param $table
-     * @param $field
-     * @param $definition
-     */
-    protected function addSqlDefinition($table, $field, $definition)
+    protected function addSqlDefinition(string $table, string $field, string $definition): void
     {
         if (!isset($this->sqlDefinitions[$table])) {
             $this->sqlDefinitions[$table] = [];
@@ -46,11 +38,7 @@ protected function addSqlDefinition($table, $field, $definition)
         $this->sqlDefinitions[$table][$field] = $definition;
     }
 
-    /**
-     * @param string $table
-     * @param array $definitions
-     */
-    protected function addSqlDefinitions($table, array $definitions)
+    protected function addSqlDefinitions(string $table, array $definitions): void
     {
         foreach ($definitions as $field => $definition) {
             $this->addSqlDefinition($table, $field, $definition);
diff --git a/Classes/Aggregate/TcaAggregate.php b/Classes/Aggregate/TcaAggregate.php
index 2778730..fb45f0e 100644
--- a/Classes/Aggregate/TcaAggregate.php
+++ b/Classes/Aggregate/TcaAggregate.php
@@ -30,7 +30,7 @@ class TcaAggregate extends AbstractAggregate implements LanguageAwareInterface,
      */
     protected $tcaFilePath = 'Configuration/TCA/';
 
-    protected function process()
+    protected function process(): void
     {
         if (empty($this->maskConfiguration)) {
             return;
@@ -72,11 +72,7 @@ protected function process()
         );
     }
 
-    /**
-     * @param array $tableConfiguration
-     * @return array
-     */
-    protected function replaceTableLabels(array $tableConfiguration)
+    protected function replaceTableLabels(array $tableConfiguration): array
     {
         $title = $this->table;
         if (empty($tableConfiguration['ctrl']['title']) || 0 !== strpos($tableConfiguration['ctrl']['title'], 'LLL:')) {
@@ -98,10 +94,7 @@ protected function replaceTableLabels(array $tableConfiguration)
         return $tableConfiguration;
     }
 
-    /**
-     * @param array $tableConfiguration
-     */
-    protected function addTableSqlDefinitions(array $tableConfiguration)
+    protected function addTableSqlDefinitions(array $tableConfiguration): void
     {
         $sqlDefinitions = [
             'uid' => 'int(11) NOT NULL auto_increment',
diff --git a/Classes/Aggregate/TcaAwareTrait.php b/Classes/Aggregate/TcaAwareTrait.php
index 16cb354..d34a4d6 100644
--- a/Classes/Aggregate/TcaAwareTrait.php
+++ b/Classes/Aggregate/TcaAwareTrait.php
@@ -41,10 +41,7 @@ trait TcaAwareTrait
      */
     protected $table;
 
-    /**
-     * @param array $fieldArray
-     */
-    protected function addFieldsSqlDefinitions(array $fieldArray)
+    protected function addFieldsSqlDefinitions(array $fieldArray): void
     {
         foreach ($fieldArray as $field => $_) {
             // Always prefer the current table and search in all definitions as fallback
@@ -68,11 +65,7 @@ protected function addFieldsSqlDefinitions(array $fieldArray)
         }
     }
 
-    /**
-     * @param array $tableConfiguration
-     * @param string $field
-     */
-    protected function addFieldSqlDefinition(array $tableConfiguration, $field)
+    protected function addFieldSqlDefinition(array $tableConfiguration, string $field): void
     {
         $table = key($tableConfiguration['sql'][$field]);
         $definition = $tableConfiguration['sql'][$field][$table][$field];
@@ -100,12 +93,7 @@ protected function addFieldSqlDefinition(array $tableConfiguration, $field)
         }
     }
 
-    /**
-     * @param array $fields
-     * @param string $table
-     * @return array
-     */
-    protected function replaceFieldLabels(array $fields, $table)
+    protected function replaceFieldLabels(array $fields, string $table): array
     {
         foreach ($fields as $field => &$configuration) {
             if (0 !== strpos($field, 'tx_mask_') || 0 === strpos(($configuration['label'] ?? ''), 'LLL:')) {
@@ -144,12 +132,7 @@ protected function replaceFieldLabels(array $fields, $table)
         return $fields;
     }
 
-    /**
-     * @param array $fields
-     * @param string $table
-     * @return array
-     */
-    protected function replaceItemsLabels(array $fields, $table)
+    protected function replaceItemsLabels(array $fields, string $table): array
     {
         foreach ($fields as $field => &$configuration) {
             if (0 !== strpos($field, 'tx_mask_') || empty($configuration['config']['items'])) {
diff --git a/Classes/Aggregate/TtContentOverridesAggregate.php b/Classes/Aggregate/TtContentOverridesAggregate.php
index 33b04f7..3d97322 100644
--- a/Classes/Aggregate/TtContentOverridesAggregate.php
+++ b/Classes/Aggregate/TtContentOverridesAggregate.php
@@ -29,7 +29,7 @@ class TtContentOverridesAggregate extends AbstractOverridesAggregate
     /**
      * Adds necessary TCA override information for tt_content table
      */
-    protected function process()
+    protected function process(): void
     {
         if (empty($GLOBALS['TCA'][$this->table])
             || empty($this->maskConfiguration[$this->table]['tca']) && empty($this->maskConfiguration[$this->table]['elements'])
@@ -45,7 +45,7 @@ protected function process()
     /**
      * @param array $tableConfiguration
      */
-    protected function addTableTypes(array $tableConfiguration)
+    protected function addTableTypes(array $tableConfiguration): void
     {
         if (empty($tableConfiguration['types']) || empty($this->maskConfiguration[$this->table]['elements'])) {
             return;
diff --git a/Classes/CodeGenerator/BackendFluidCodeGenerator.php b/Classes/CodeGenerator/BackendFluidCodeGenerator.php
index 9f04dd5..202519e 100644
--- a/Classes/CodeGenerator/BackendFluidCodeGenerator.php
+++ b/Classes/CodeGenerator/BackendFluidCodeGenerator.php
@@ -24,12 +24,8 @@ class BackendFluidCodeGenerator
 {
     /**
      * Generate Fluid template according to field type
-     *
-     * @param string $table
-     * @param string $field
-     * @return string
      */
-    public function generateFluid($table, $field)
+    public function generateFluid(string $table, string $field): string
     {
         if (!isset($GLOBALS['TCA'][$table]['columns'][$field])) {
             return '';
@@ -67,13 +63,7 @@ public function generateFluid($table, $field)
         return $content;
     }
 
-    /**
-     * @param string $field
-     * @param array $fieldConfiguration
-     * @param string $iteratorName
-     * @return string
-     */
-    protected function getInlineFluid($field, array $fieldConfiguration, $iteratorName = '')
+    protected function getInlineFluid(string $field, array $fieldConfiguration, string $iteratorName = ''): string
     {
         $foreignTable = $fieldConfiguration['config']['foreign_table'];
         $foreignLabelField = $GLOBALS['TCA'][$foreignTable]['ctrl']['label'];
@@ -124,12 +114,7 @@ protected function getInlineFluid($field, array $fieldConfiguration, $iteratorNa
         return $content;
     }
 
-    /**
-     * @param string $field
-     * @param array $fieldConfiguration
-     * @return string
-     */
-    protected function getSelectFluid($field, array $fieldConfiguration)
+    protected function getSelectFluid(string $field, array $fieldConfiguration): string
     {
         if (empty($fieldConfiguration['config']['maxitems']) || 1 === (int)$fieldConfiguration['config']['maxitems']) {
             $content = <<<EOS
@@ -150,10 +135,7 @@ protected function getSelectFluid($field, array $fieldConfiguration)
         return $content;
     }
 
-    /**
-     * @return string
-     */
-    protected function getSysFileFluid()
+    protected function getSysFileFluid(): string
     {
         if (version_compare(TYPO3_version, '8.6.0', '>=')) {
             $content = <<<EOS
diff --git a/Classes/CodeGenerator/HtmlCodeGenerator.php b/Classes/CodeGenerator/HtmlCodeGenerator.php
index 634a16a..8b6fa8d 100644
--- a/Classes/CodeGenerator/HtmlCodeGenerator.php
+++ b/Classes/CodeGenerator/HtmlCodeGenerator.php
@@ -50,12 +50,8 @@ public function __construct(StorageRepository $storageRepository = null, FieldHe
 
     /**
      * Generates Fluid HTML for Contentelements
-     *
-     * @param string $key
-     * @param string $table
-     * @return string
      */
-    public function generateHtml($key, $table = 'tt_content')
+    public function generateHtml(string $key): string
     {
         $storage = $this->storageRepository->loadElement('tt_content', $key);
         $html = '';
@@ -74,15 +70,13 @@ public function generateHtml($key, $table = 'tt_content')
 
     /**
      * Generates HTML for a field
-     *
-     * @param string $fieldKey
-     * @param string $elementKey
-     * @param string $table
-     * @param string $datafield
-     * @return string
      */
-    protected function generateFieldHtml($fieldKey, $elementKey, $table = 'tt_content', $datafield = 'data')
-    {
+    protected function generateFieldHtml(
+        string $fieldKey,
+        string $elementKey,
+        string $table = 'tt_content',
+        string $datafield = 'data'
+    ): string {
         $formType = strtolower($this->fieldHelper->getFormType($fieldKey, $elementKey, $table));
         if (in_array($formType, ['linebreak', 'tab'], true)) {
             return '';
diff --git a/Classes/Controller/ExportController.php b/Classes/Controller/ExportController.php
index 2bbfef9..609acb6 100644
--- a/Classes/Controller/ExportController.php
+++ b/Classes/Controller/ExportController.php
@@ -115,6 +115,8 @@ public function listAction($vendorName = '', $extensionName = '', $elements = []
      * @param string $vendorName
      * @param string $extensionName
      * @param array $elements
+     * @throws \TYPO3\CMS\Extbase\Mvc\Exception\NoSuchArgumentException
+     * @throws \TYPO3\CMS\Extbase\Mvc\Exception\StopActionException
      */
     public function saveAction($vendorName = '', $extensionName = '', $elements = [])
     {
@@ -178,6 +180,8 @@ public function downloadAction($vendorName, $extensionName, $elements)
      * @param string $vendorName
      * @param string $extensionName
      * @param array $elements
+     * @throws \TYPO3\CMS\Extbase\Mvc\Exception\StopActionException
+     * @throws \TYPO3\CMS\Extbase\Object\Exception
      */
     public function installAction($vendorName, $extensionName, $elements)
     {
@@ -224,10 +228,7 @@ public function installAction($vendorName, $extensionName, $elements)
         $this->redirect('list');
     }
 
-    /**
-     * @return string
-     */
-    protected function getExtensionName()
+    protected function getExtensionName(): string
     {
         $extensionName = $this->defaultExtensionName;
 
@@ -238,7 +239,9 @@ protected function getExtensionName()
             $extensionName = $this->maskConfiguration['mask_export']['extensionName'];
         } else {
             $backendUser = $this->getBackendUser();
-            if (!empty($backendUser->uc['mask_export']['extensionName'])) {
+            if ($backendUser instanceof BackendUserAuthentication
+                && !empty($backendUser->uc['mask_export']['extensionName'])
+            ) {
                 $extensionName = $backendUser->uc['mask_export']['extensionName'];
             }
         }
@@ -246,10 +249,7 @@ protected function getExtensionName()
         return $extensionName;
     }
 
-    /**
-     * @return string
-     */
-    protected function getVendorName()
+    protected function getVendorName(): string
     {
         $vendorName = GeneralUtility::underscoredToUpperCamelCase($this->defaultExtensionName);
 
@@ -271,7 +271,7 @@ protected function getVendorName()
     /**
      * @return string[]
      */
-    protected function getElements()
+    protected function getElements(): array
     {
         $elements = [];
 
@@ -290,13 +290,7 @@ protected function getElements()
         return $elements;
     }
 
-    /**
-     * @param string $vendorName
-     * @param string $extensionName
-     * @param array $elements
-     * @return array
-     */
-    protected function getFiles($vendorName, $extensionName, $elements)
+    protected function getFiles(string $vendorName, string $extensionName, array $elements): array
     {
         $aggregatedMaskConfiguration = $this->prepareConfiguration($vendorName, $extensionName, $elements);
 
@@ -318,7 +312,7 @@ protected function getFiles($vendorName, $extensionName, $elements)
         return $files;
     }
 
-    protected function prepareConfiguration(string $vendorName, string $extensionName, array $elements)
+    protected function prepareConfiguration(string $vendorName, string $extensionName, array $elements): array
     {
         $aggregatedConfiguration = $this->maskConfiguration;
 
@@ -391,11 +385,7 @@ protected function prepareConfiguration(string $vendorName, string $extensionNam
         return $aggregatedConfiguration;
     }
 
-    /**
-     * @param array $files
-     * @param string $extensionPath
-     */
-    protected function writeExtensionFilesToPath(array $files, $extensionPath)
+    protected function writeExtensionFilesToPath(array $files, string $extensionPath): void
     {
         if (file_exists($extensionPath)) {
             $finder = new Finder();
@@ -424,13 +414,7 @@ protected function writeExtensionFilesToPath(array $files, $extensionPath)
         }
     }
 
-    /**
-     * @param string $vendorName
-     * @param string $extensionKey
-     * @param array $files
-     * @return array
-     */
-    protected function replaceExtensionInformation($vendorName, $extensionKey, array $files)
+    protected function replaceExtensionInformation(string $vendorName, string $extensionKey, array $files): array
     {
         $newFiles = [];
         foreach ($files as $file => $fileContent) {
@@ -444,13 +428,7 @@ protected function replaceExtensionInformation($vendorName, $extensionKey, array
         return $newFiles;
     }
 
-    /**
-     * @param string $vendorName
-     * @param string $extensionKey
-     * @param string $string
-     * @return string
-     */
-    protected function replaceExtensionKey($vendorName, $extensionKey, $string)
+    protected function replaceExtensionKey(string $vendorName, string $extensionKey, string $string): string
     {
         $camelCasedExtensionKey = GeneralUtility::underscoredToUpperCamelCase($extensionKey);
         $lowercaseExtensionKey = strtolower($camelCasedExtensionKey);
@@ -504,11 +482,7 @@ protected function replaceExtensionKey($vendorName, $extensionKey, $string)
         return $string;
     }
 
-    /**
-     * @param array $files
-     * @return array
-     */
-    protected function sortFiles(array $files)
+    protected function sortFiles(array $files): array
     {
         uksort($files, static function ($a, $b) {
             if (substr_count($a, '/') === 0 && substr_count($b, '/') > 0) {
@@ -535,10 +509,7 @@ protected function sortFiles(array $files)
         return $files;
     }
 
-    /**
-     * @return BackendUserAuthentication
-     */
-    protected function getBackendUser()
+    protected function getBackendUser(): ?BackendUserAuthentication
     {
         return $GLOBALS['BE_USER'];
     }
diff --git a/Classes/FileCollection/AbstractFileCollection.php b/Classes/FileCollection/AbstractFileCollection.php
index e783cc6..14e914c 100644
--- a/Classes/FileCollection/AbstractFileCollection.php
+++ b/Classes/FileCollection/AbstractFileCollection.php
@@ -39,10 +39,7 @@ public function __construct(array $aggregateCollection)
         $this->aggregateCollection = $aggregateCollection;
     }
 
-    /**
-     * @return array
-     */
-    public function getFiles()
+    public function getFiles(): array
     {
         if (null === $this->files) {
             $this->files = $this->processAggregateCollection();
@@ -51,8 +48,5 @@ public function getFiles()
         return $this->files;
     }
 
-    /**
-     * @return array
-     */
-    abstract protected function processAggregateCollection();
+    abstract protected function processAggregateCollection(): array;
 }
diff --git a/Classes/FileCollection/FileCollection.php b/Classes/FileCollection/FileCollection.php
index 116e5a9..925f750 100644
--- a/Classes/FileCollection/FileCollection.php
+++ b/Classes/FileCollection/FileCollection.php
@@ -42,10 +42,7 @@ public function __construct(array $fileCollectionClassNames, array $aggregateCol
         $this->aggregateCollection = $aggregateCollection;
     }
 
-    /**
-     * @return array
-     */
-    public function getFiles()
+    public function getFiles(): array
     {
         if (null === $this->files) {
             $this->initializeFiles();
@@ -57,7 +54,7 @@ public function getFiles()
     /**
      * Initializes aggregate objects
      */
-    protected function initializeFiles()
+    protected function initializeFiles(): void
     {
         $this->files = [];
         foreach ($this->fileCollectionClassNames as $className) {
diff --git a/Classes/FileCollection/LanguageFileCollection.php b/Classes/FileCollection/LanguageFileCollection.php
index 230d458..b5562f8 100644
--- a/Classes/FileCollection/LanguageFileCollection.php
+++ b/Classes/FileCollection/LanguageFileCollection.php
@@ -22,9 +22,9 @@
 class LanguageFileCollection extends AbstractFileCollection
 {
     /**
-     * @return array
+     * @throws \DOMException
      */
-    protected function processAggregateCollection()
+    protected function processAggregateCollection(): array
     {
         $labels = [];
         foreach ($this->aggregateCollection as $aggregate) {
@@ -44,10 +44,9 @@ protected function processAggregateCollection()
     }
 
     /**
-     * @param array $body
-     * @return string
+     * @throws \DOMException
      */
-    protected function generateLanguageFile(array $body)
+    protected function generateLanguageFile(array $body): string
     {
         $domDocument = new \DOMDocument('1.0', 'utf-8');
         $domDocument->formatOutput = true;
diff --git a/Classes/FileCollection/PhpFileCollection.php b/Classes/FileCollection/PhpFileCollection.php
index 86528b1..e1e0bf7 100644
--- a/Classes/FileCollection/PhpFileCollection.php
+++ b/Classes/FileCollection/PhpFileCollection.php
@@ -35,10 +35,7 @@ public function __construct(array $aggregateCollection, PhpFileFlagResolver $php
         $this->phpFileFlagResolver = $phpFileFlagResolver ?: GeneralUtility::makeInstance(PhpFileFlagResolver::class);
     }
 
-    /**
-     * @return array
-     */
-    protected function processAggregateCollection()
+    protected function processAggregateCollection(): array
     {
         $fileInformation = [];
         foreach ($this->aggregateCollection as $aggregate) {
diff --git a/Classes/FileCollection/PlainTextFileCollection.php b/Classes/FileCollection/PlainTextFileCollection.php
index b873fdc..118ec95 100644
--- a/Classes/FileCollection/PlainTextFileCollection.php
+++ b/Classes/FileCollection/PlainTextFileCollection.php
@@ -21,10 +21,7 @@
 
 class PlainTextFileCollection extends AbstractFileCollection
 {
-    /**
-     * @return array
-     */
-    protected function processAggregateCollection()
+    protected function processAggregateCollection(): array
     {
         $files = [];
         foreach ($this->aggregateCollection as $aggregate) {
diff --git a/Classes/FileCollection/SqlFileCollection.php b/Classes/FileCollection/SqlFileCollection.php
index 774c419..548c0e5 100644
--- a/Classes/FileCollection/SqlFileCollection.php
+++ b/Classes/FileCollection/SqlFileCollection.php
@@ -41,10 +41,7 @@ public function __construct(array $aggregateCollection, DefaultTcaSchema $defaul
         $this->defaultSchema = $defaultSchema ?: GeneralUtility::makeInstance(DefaultTcaSchema::class);
     }
 
-    /**
-     * @return array
-     */
-    protected function processAggregateCollection()
+    protected function processAggregateCollection(): array
     {
         $files = [];
         $sqlDefinitions = [];
diff --git a/Classes/FlagResolver/AbstractFlagResolver.php b/Classes/FlagResolver/AbstractFlagResolver.php
index 3d6f21b..e8ebbcf 100644
--- a/Classes/FlagResolver/AbstractFlagResolver.php
+++ b/Classes/FlagResolver/AbstractFlagResolver.php
@@ -36,11 +36,7 @@ public function __construct(DependencyOrderingService $dependencyOrderingService
         $this->flags = $dependencyOrderingService->orderByDependencies($this->flags);
     }
 
-    /**
-     * @param array $fileInformation
-     * @return array
-     */
-    public function resolveFlags(array $fileInformation)
+    public function resolveFlags(array $fileInformation): array
     {
         $files = array_map(
             static function ($information) {
diff --git a/Classes/FlagResolver/FlagInterface.php b/Classes/FlagResolver/FlagInterface.php
index ab39300..1b178bd 100644
--- a/Classes/FlagResolver/FlagInterface.php
+++ b/Classes/FlagResolver/FlagInterface.php
@@ -19,15 +19,7 @@
 
 interface FlagInterface
 {
-    /**
-     * @param int $flags
-     * @return bool
-     */
-    public function isEnabled($flags);
+    public function isEnabled(int $flags): bool;
 
-    /**
-     * @param string $content
-     * @return string
-     */
-    public function execute($content);
+    public function execute(string $content): string;
 }
diff --git a/Classes/FlagResolver/FlagResolverInterface.php b/Classes/FlagResolver/FlagResolverInterface.php
index 93b5ef2..adc9556 100644
--- a/Classes/FlagResolver/FlagResolverInterface.php
+++ b/Classes/FlagResolver/FlagResolverInterface.php
@@ -19,9 +19,5 @@
 
 interface FlagResolverInterface
 {
-    /**
-     * @param array $fileInformation
-     * @return array
-     */
-    public function resolveFlags(array $fileInformation);
+    public function resolveFlags(array $fileInformation): array;
 }
diff --git a/Classes/FlagResolver/PhpFileFlag/ClosureFunctionFlag.php b/Classes/FlagResolver/PhpFileFlag/ClosureFunctionFlag.php
index 47e9fd9..784db5e 100644
--- a/Classes/FlagResolver/PhpFileFlag/ClosureFunctionFlag.php
+++ b/Classes/FlagResolver/PhpFileFlag/ClosureFunctionFlag.php
@@ -22,16 +22,12 @@
 
 class ClosureFunctionFlag implements FlagInterface
 {
-    /**
-     * @param int $flags
-     * @return bool
-     */
-    public function isEnabled($flags)
+    public function isEnabled(int $flags): bool
     {
         return ($flags & PhpAwareInterface::PHPFILE_CLOSURE_FUNCTION) === PhpAwareInterface::PHPFILE_CLOSURE_FUNCTION;
     }
 
-    public function execute($content)
+    public function execute(string $content): string
     {
         return <<<EOS
 call_user_func(static function () {
diff --git a/Classes/FlagResolver/PhpFileFlag/DefinedTypo3ModeFlag.php b/Classes/FlagResolver/PhpFileFlag/DefinedTypo3ModeFlag.php
index b6ecd0b..bbba039 100644
--- a/Classes/FlagResolver/PhpFileFlag/DefinedTypo3ModeFlag.php
+++ b/Classes/FlagResolver/PhpFileFlag/DefinedTypo3ModeFlag.php
@@ -22,20 +22,12 @@
 
 class DefinedTypo3ModeFlag implements FlagInterface
 {
-    /**
-     * @param int $flags
-     * @return bool
-     */
-    public function isEnabled($flags)
+    public function isEnabled(int $flags): bool
     {
         return ($flags & PhpAwareInterface::PHPFILE_DEFINED_TYPO3_MODE) === PhpAwareInterface::PHPFILE_DEFINED_TYPO3_MODE;
     }
 
-    /**
-     * @param string $content
-     * @return string
-     */
-    public function execute($content)
+    public function execute(string $content): string
     {
         return <<<EOS
 defined('TYPO3_MODE') || die();
diff --git a/Classes/FlagResolver/PhpFileFlag/PhpStartTagFlag.php b/Classes/FlagResolver/PhpFileFlag/PhpStartTagFlag.php
index b2b837e..8310f7f 100644
--- a/Classes/FlagResolver/PhpFileFlag/PhpStartTagFlag.php
+++ b/Classes/FlagResolver/PhpFileFlag/PhpStartTagFlag.php
@@ -21,16 +21,12 @@
 
 class PhpStartTagFlag implements FlagInterface
 {
-    /**
-     * @param int $flags
-     * @return bool
-     */
-    public function isEnabled($flags)
+    public function isEnabled(int $flags): bool
     {
         return true;
     }
 
-    public function execute($content)
+    public function execute(string $content): string
     {
         return '<?php' . PHP_EOL . $content;
     }
diff --git a/Tests/Functional/Controller/AbstractExportControllerTestCase.php b/Tests/Functional/Controller/AbstractExportControllerTestCase.php
index b016258..851697a 100644
--- a/Tests/Functional/Controller/AbstractExportControllerTestCase.php
+++ b/Tests/Functional/Controller/AbstractExportControllerTestCase.php
@@ -124,7 +124,7 @@ protected function setUp(): void
     /**
      * As the export extension cannot be installed over extensionmanager APi, this function loads data manually
      */
-    protected function installExtension()
+    protected function installExtension(): void
     {
         // Require PHP files and take care of TCA configuration
         $_EXTKEY = 'mask_example_export';
diff --git a/Tests/Functional/Controller/BackendPreview/ExportControllerTest.php b/Tests/Functional/Controller/BackendPreview/ExportControllerTest.php
index 5280e61..4d35f47 100644
--- a/Tests/Functional/Controller/BackendPreview/ExportControllerTest.php
+++ b/Tests/Functional/Controller/BackendPreview/ExportControllerTest.php
@@ -35,7 +35,7 @@ class ExportControllerTest extends AbstractExportControllerTestCase
     /**
      * @test
      */
-    public function checkFluidTemplatePathInBackendPreview()
+    public function checkFluidTemplatePathInBackendPreview(): void
     {
         $this->assertArrayHasKey('Configuration/TsConfig/Page/BackendPreview.tsconfig', $this->files);
 
@@ -69,7 +69,7 @@ public function checkFluidTemplatePathInBackendPreview()
     /**
      * @test
      */
-    public function validateProcessedRowDataFromPageLayoutViewDrawItem()
+    public function validateProcessedRowDataFromPageLayoutViewDrawItem(): void
     {
         $className = 'IchHabRecht\\MaskExampleExport\\Hooks\\PageLayoutViewDrawItem';
         $this->installExtension();
@@ -158,7 +158,7 @@ public function validateProcessedRowDataFromPageLayoutViewDrawItem()
     /**
      * @test
      */
-    public function validateFluidTemplateForSelectboxFields()
+    public function validateFluidTemplateForSelectboxFields(): void
     {
         $this->assertArrayHasKey('Resources/Private/Backend/Templates/Content/Simple-element.html', $this->files);
         $this->assertStringContainsString(
diff --git a/Tests/Functional/Controller/Configuration/ExportControllerTest.php b/Tests/Functional/Controller/Configuration/ExportControllerTest.php
index fff591b..f238315 100644
--- a/Tests/Functional/Controller/Configuration/ExportControllerTest.php
+++ b/Tests/Functional/Controller/Configuration/ExportControllerTest.php
@@ -26,7 +26,7 @@ class ExportControllerTest extends AbstractExportControllerTestCase
     /**
      * @test
      */
-    public function ensureTypo3DependencyInExtEmConf()
+    public function ensureTypo3DependencyInExtEmConf(): void
     {
         $this->assertArrayHasKey('ext_emconf.php', $this->files);
 
@@ -53,7 +53,7 @@ public function ensureTypo3DependencyInExtEmConf()
     /**
      * @test
      */
-    public function ensureExtensionNameIsReplacedInComposerJson()
+    public function ensureExtensionNameIsReplacedInComposerJson(): void
     {
         $this->assertArrayHasKey('composer.json', $this->files);
 
@@ -100,7 +100,7 @@ public function ensureExtensionNameIsReplacedInComposerJson()
     /**
      * @test
      */
-    public function ensureMaskConfigurationIsNotChanged()
+    public function ensureMaskConfigurationIsNotChanged(): void
     {
         $this->assertArrayHasKey('Configuration/Mask/mask.json', $this->files);
 
@@ -110,10 +110,10 @@ public function ensureMaskConfigurationIsNotChanged()
         );
     }
 
-    /*
+    /**
      * @test
      */
-    public function ensureMaskConfigurationIsNotExported()
+    public function ensureMaskConfigurationIsNotExported(): void
     {
         $this->assertArrayHasKey('ext_tables.php', $this->files);
         $this->assertArrayHasKey('ext_tables.sql', $this->files);
diff --git a/Tests/Functional/Controller/DataProvider/ExportControllerTest.php b/Tests/Functional/Controller/DataProvider/ExportControllerTest.php
index 57586ac..3e690f2 100644
--- a/Tests/Functional/Controller/DataProvider/ExportControllerTest.php
+++ b/Tests/Functional/Controller/DataProvider/ExportControllerTest.php
@@ -32,15 +32,7 @@
 
 class ExportControllerTest extends AbstractExportControllerTestCase
 {
-    protected function setUp(): void
-    {
-        parent::setUp();
-    }
-
-    /**
-     * @return array
-     */
-    public function tcaColPosItemDataProviderAddsNestedContentColPosForSupportedRecordsDataProvider()
+    public function tcaColPosItemDataProviderAddsNestedContentColPosForSupportedRecordsDataProvider(): array
     {
         return [
             'Add nested inline record' => [
@@ -336,7 +328,7 @@ public function tcaColPosItemDataProviderAddsNestedContentColPosForSupportedReco
      * @param array $formDataCompilerInput
      * @param bool $expectation
      */
-    public function tcaColPosItemDataProviderAddsNestedContentColPosForSupportedRecords(array $formDataCompilerInput, $expectation)
+    public function tcaColPosItemDataProviderAddsNestedContentColPosForSupportedRecords(array $formDataCompilerInput, $expectation): void
     {
         $this->installExtension();
 
@@ -383,10 +375,7 @@ public function tcaColPosItemDataProviderAddsNestedContentColPosForSupportedReco
         }
     }
 
-    /**
-     * @return array
-     */
-    public function tcaCTypeItemDataProviderRemovesRestrictedCTypesForSupportedRecordsDataProvider()
+    public function tcaCTypeItemDataProviderRemovesRestrictedCTypesForSupportedRecordsDataProvider(): array
     {
         return [
             'Add nested inline record' => [
@@ -626,7 +615,7 @@ public function tcaCTypeItemDataProviderRemovesRestrictedCTypesForSupportedRecor
      * @param array $formDataCompilerInput
      * @param bool $expectation
      */
-    public function tcaCTypeItemDataProviderRemovesRestrictedCTypesForSupportedRecords(array $formDataCompilerInput, $expectation)
+    public function tcaCTypeItemDataProviderRemovesRestrictedCTypesForSupportedRecords(array $formDataCompilerInput, $expectation): void
     {
         $this->installExtension();
 
@@ -652,10 +641,7 @@ public function tcaCTypeItemDataProviderRemovesRestrictedCTypesForSupportedRecor
         }
     }
 
-    /**
-     * @return array
-     */
-    public function tcaCTypeItemDataProviderRemovesRestrictedCTypesForMultiNestedRecordsDataProvider()
+    public function tcaCTypeItemDataProviderRemovesRestrictedCTypesForMultiNestedRecordsDataProvider(): array
     {
         return [
             'Add multi-nested inline record' => [
@@ -801,7 +787,7 @@ public function tcaCTypeItemDataProviderRemovesRestrictedCTypesForMultiNestedRec
      * @param array $formDataCompilerInput
      * @param bool $expectation
      */
-    public function tcaCTypeItemDataProviderRemovesRestrictedCTypesForMultiNestedRecords(array $formDataCompilerInput, $expectation)
+    public function tcaCTypeItemDataProviderRemovesRestrictedCTypesForMultiNestedRecords(array $formDataCompilerInput, $expectation): void
     {
         $this->installExtension();
 
diff --git a/Tests/Functional/Controller/FlagResolver/PhpFileFlagResolverTest.php b/Tests/Functional/Controller/FlagResolver/PhpFileFlagResolverTest.php
index 47a272c..418b24d 100644
--- a/Tests/Functional/Controller/FlagResolver/PhpFileFlagResolverTest.php
+++ b/Tests/Functional/Controller/FlagResolver/PhpFileFlagResolverTest.php
@@ -23,10 +23,7 @@
 
 class PhpFileFlagResolverTest extends AbstractExportControllerTestCase
 {
-    /**
-     * @return array
-     */
-    public function closureFunctionIsAppliedDataProvider()
+    public function closureFunctionIsAppliedDataProvider(): array
     {
         return [
             'ext_localconf.php' => [
@@ -46,7 +43,7 @@ public function closureFunctionIsAppliedDataProvider()
      * @dataProvider closureFunctionIsAppliedDataProvider
      * @param string $filePattern
      */
-    public function closureFunctionIsApplied($filePattern)
+    public function closureFunctionIsApplied(string $filePattern): void
     {
         $files = [];
         foreach ($this->files as $file => $content) {
@@ -62,10 +59,7 @@ public function closureFunctionIsApplied($filePattern)
         }
     }
 
-    /**
-     * @return array
-     */
-    public function definedTypo3ModeIsAppliedDataProvider()
+    public function definedTypo3ModeIsAppliedDataProvider(): array
     {
         return [
             'ext_localconf.php' => [
@@ -85,7 +79,7 @@ public function definedTypo3ModeIsAppliedDataProvider()
      * @dataProvider definedTypo3ModeIsAppliedDataProvider
      * @param string $filePattern
      */
-    public function definedTypo3ModeIsApplied($filePattern)
+    public function definedTypo3ModeIsApplied(string $filePattern): void
     {
         $files = [];
         foreach ($this->files as $file => $content) {
diff --git a/Tests/Functional/Controller/MaskConfiguration/EmptyColumnsTest.php b/Tests/Functional/Controller/MaskConfiguration/EmptyColumnsTest.php
index ebef2ad..7fcf9a8 100644
--- a/Tests/Functional/Controller/MaskConfiguration/EmptyColumnsTest.php
+++ b/Tests/Functional/Controller/MaskConfiguration/EmptyColumnsTest.php
@@ -33,7 +33,7 @@ protected function setUp(): void
     /**
      * @test
      */
-    public function tempColumnsCodeNotGeneratedIfNoColumnsAvailable()
+    public function tempColumnsCodeNotGeneratedIfNoColumnsAvailable(): void
     {
         $this->configurationToUseInTestInstance['EXTENSIONS']['mask']['json'] = 'typo3conf/ext/mask_export/Tests/Functional/Fixtures/Configuration/mask-empty-columns.json';
 
diff --git a/Tests/Functional/Controller/MaskConfiguration/EmptyMaskConfigurationTest.php b/Tests/Functional/Controller/MaskConfiguration/EmptyMaskConfigurationTest.php
index 6173e73..252ee18 100644
--- a/Tests/Functional/Controller/MaskConfiguration/EmptyMaskConfigurationTest.php
+++ b/Tests/Functional/Controller/MaskConfiguration/EmptyMaskConfigurationTest.php
@@ -33,7 +33,7 @@ protected function setUp(): void
     /**
      * @test
      */
-    public function basicExtensionFilesExistsWithoutMaskConfiguration()
+    public function basicExtensionFilesExistsWithoutMaskConfiguration(): void
     {
         $this->configurationToUseInTestInstance['EXTENSIONS']['mask']['json'] = 'typo3conf/mask.json';
 
diff --git a/Tests/Functional/Controller/NewContentElementWizard/ExportControllerTest.php b/Tests/Functional/Controller/NewContentElementWizard/ExportControllerTest.php
index d5b73c7..98397b6 100644
--- a/Tests/Functional/Controller/NewContentElementWizard/ExportControllerTest.php
+++ b/Tests/Functional/Controller/NewContentElementWizard/ExportControllerTest.php
@@ -26,7 +26,7 @@ class ExportControllerTest extends AbstractExportControllerTestCase
     /**
      * @test
      */
-    public function hiddenContentElementsIgnoredInExport()
+    public function hiddenContentElementsIgnoredInExport(): void
     {
         $this->assertArrayHasKey('Configuration/TsConfig/Page/NewContentElementWizard.tsconfig', $this->files);
         $this->assertStringNotContainsString(
diff --git a/Tests/Functional/Controller/Ressources/ExportControllerTest.php b/Tests/Functional/Controller/Ressources/ExportControllerTest.php
index c14e3ee..f7bf80b 100644
--- a/Tests/Functional/Controller/Ressources/ExportControllerTest.php
+++ b/Tests/Functional/Controller/Ressources/ExportControllerTest.php
@@ -28,7 +28,7 @@ class ExportControllerTest extends AbstractExportControllerTestCase
     /**
      * @test
      */
-    public function ensureContentElementIconFromPreviewFolderInExport()
+    public function ensureContentElementIconFromPreviewFolderInExport(): void
     {
         $this->assertArrayHasKey('Resources/Public/Icons/Content/simple-element.png', $this->files);
 
@@ -41,7 +41,7 @@ public function ensureContentElementIconFromPreviewFolderInExport()
     /**
      * @test
      */
-    public function ensureContentElementIconFromFallbackPathInExport()
+    public function ensureContentElementIconFromFallbackPathInExport(): void
     {
         $this->assertArrayHasKey('Resources/Public/Icons/Content/nested-content-elements.png', $this->files);
 
@@ -54,7 +54,7 @@ public function ensureContentElementIconFromFallbackPathInExport()
     /**
      * @test
      */
-    public function extensionIconIsUsedAsDefaultContentElementIcon()
+    public function extensionIconIsUsedAsDefaultContentElementIcon(): void
     {
         $this->assertArrayHasKey('Resources/Public/Icons/Content/default-extension-icon.svg', $this->files);
 
@@ -67,7 +67,7 @@ public function extensionIconIsUsedAsDefaultContentElementIcon()
     /**
      * @test
      */
-    public function contentElementsHaveRegisteredIconIdentifier()
+    public function contentElementsHaveRegisteredIconIdentifier(): void
     {
         $maskConfiguration = json_decode(file_get_contents(__DIR__ . '/../../Fixtures/Configuration/mask-default.json'), true);
         $this->assertNotEmpty($maskConfiguration['tt_content']['elements']);
@@ -94,7 +94,7 @@ public function contentElementsHaveRegisteredIconIdentifier()
     /**
      * @test
      */
-    public function itemsLabelsAreMovedToLocallangFile()
+    public function itemsLabelsAreMovedToLocallangFile(): void
     {
         $this->assertArrayHasKey('Configuration/TCA/Overrides/tt_content.php', $this->files);
         $this->assertArrayHasKey('Resources/Private/Language/locallang_db.xlf', $this->files);
diff --git a/Tests/Functional/Controller/TypoScript/ExportControllerTest.php b/Tests/Functional/Controller/TypoScript/ExportControllerTest.php
index 399e0a7..41af788 100644
--- a/Tests/Functional/Controller/TypoScript/ExportControllerTest.php
+++ b/Tests/Functional/Controller/TypoScript/ExportControllerTest.php
@@ -26,7 +26,7 @@ class ExportControllerTest extends AbstractExportControllerTestCase
     /**
      * @test
      */
-    public function checkFluidTemplatePathsInTypoScript()
+    public function checkFluidTemplatePathsInTypoScript(): void
     {
         $this->assertArrayHasKey('Configuration/TypoScript/setup.typoscript', $this->files);
 
@@ -63,7 +63,7 @@ public function checkFluidTemplatePathsInTypoScript()
     /**
      * @test
      */
-    public function ensureConstantsAreInitializedInTypoScript()
+    public function ensureConstantsAreInitializedInTypoScript(): void
     {
         $this->assertArrayHasKey('Configuration/TypoScript/constants.typoscript', $this->files);
         $this->assertArrayHasKey('Configuration/TypoScript/setup.typoscript', $this->files);
@@ -85,7 +85,7 @@ public function ensureConstantsAreInitializedInTypoScript()
     /**
      * @test
      */
-    public function ensureDataProcessingWhereClauseIsBuiltCompletely()
+    public function ensureDataProcessingWhereClauseIsBuiltCompletely(): void
     {
         $this->assertArrayHasKey('Configuration/TypoScript/setup.typoscript', $this->files);
         $this->assertStringContainsString(
diff --git a/Tests/Unit/FileCollection/PhpFileCollectionTest.php b/Tests/Unit/FileCollection/PhpFileCollectionTest.php
index e1a65eb..d8c33b1 100644
--- a/Tests/Unit/FileCollection/PhpFileCollectionTest.php
+++ b/Tests/Unit/FileCollection/PhpFileCollectionTest.php
@@ -28,7 +28,7 @@ class PhpFileCollectionTest extends UnitTestCase
     /**
      * @test
      */
-    public function getFilesCombinesPhpFileFlags()
+    public function getFilesCombinesPhpFileFlags(): void
     {
         $aggregateOne = $this->prophesize(PhpAwareInterface::class);
         $aggregateOne->getPhpFiles()->willReturn(