Simplify RenameEntriesTransformer to work only on one entry

src/core/etl/src/Flow/ETL/DSL/Transform.php

@@ -16,8 +16,7 @@
 use Flow\ETL\Transformer;
 use Flow\ETL\Transformer\ArrayKeysStyleConverterTransformer;
 use Flow\ETL\Transformer\KeepEntriesTransformer;
-use Flow\ETL\Transformer\Rename\EntryRename;
-use Flow\ETL\Transformer\RenameEntriesTransformer;
+use Flow\ETL\Transformer\RenameEntryTransformer;
 use Flow\ETL\Transformer\StyleConverter\StringStyles;
 
 /**
@@ -149,7 +148,7 @@ final public static function remove(string|Reference ...$entry) : Transformer
 
     final public static function rename(string $from, string $to) : Transformer
     {
-        return new RenameEntriesTransformer(new EntryRename($from, $to));
+        return new RenameEntryTransformer($from, $to);
     }
 
     public static function rename_all_case(bool $upper = false, bool $lower = false, bool $ucfirst = false, bool $ucwords = false) : Transformer

src/core/etl/src/Flow/ETL/Transformer/RenameEntryTransformer.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Flow\ETL\Transformer;
+
+use Flow\ETL\FlowContext;
+use Flow\ETL\Row;
+use Flow\ETL\Rows;
+use Flow\ETL\Transformer;
+
+/**
+ * @implements Transformer<array{from: string, to: string}>
+ */
+final class RenameEntryTransformer implements Transformer
+{
+    public function __construct(private readonly string $from, private readonly string $to)
+    {
+    }
+
+    public function __serialize() : array
+    {
+        return [
+            'from' => $this->from,
+            'to' => $this->to,
+        ];
+    }
+
+    public function __unserialize(array $data) : void
+    {
+        $this->from = $data['from'];
+        $this->to = $data['to'];
+    }
+
+    public function transform(Rows $rows, FlowContext $context) : Rows
+    {
+        return $rows->map(fn (Row $row) : Row => $row->rename($this->from, $this->to));
+    }
+}

src/core/etl/tests/Flow/ETL/Tests/Unit/Transformer/RenameEntriesTransformerTest.php → src/core/etl/tests/Flow/ETL/Tests/Unit/Transformer/RenameEntryTransformerTest.php

@@ -11,7 +11,7 @@
 use Flow\ETL\Rows;
 use PHPUnit\Framework\TestCase;
 
-final class RenameEntriesTransformerTest extends TestCase
+final class RenameEntryTransformerTest extends TestCase
 {
     public function test_renaming_entries() : void
     {