diff --git a/.gitignore b/.gitignore
index c94c5d02..914810cd 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,7 +9,7 @@ target/
.attach*
# Stuff that I generate when I have lost all hope in the world
-/build.log
+/*.log
temp/
# Version backups after running ./mvnw versions:set
diff --git a/src/it/gh-132-duplicate-maven-dependencies/invoker.properties b/src/it/gh-132-duplicate-maven-dependencies/invoker.properties
new file mode 100644
index 00000000..542474dd
--- /dev/null
+++ b/src/it/gh-132-duplicate-maven-dependencies/invoker.properties
@@ -0,0 +1,17 @@
+#
+# Copyright (C) 2023 - 2024, Ashley Scopes.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+invoker.goals=clean verify --projects some-project --also-make
diff --git a/src/it/gh-132-duplicate-maven-dependencies/pom.xml b/src/it/gh-132-duplicate-maven-dependencies/pom.xml
new file mode 100644
index 00000000..a072bcec
--- /dev/null
+++ b/src/it/gh-132-duplicate-maven-dependencies/pom.xml
@@ -0,0 +1,108 @@
+
+
+
+ 4.0.0
+
+ org.example
+ some-parent
+ 0.0.1-SNAPSHOT
+ pom
+
+
+ some-dependency-1
+ some-dependency-2
+ some-dependency-3
+ some-dependency-4
+ some-project
+
+
+
+ 5.10.1
+ 4.26.0
+ 2.37.0
+
+ 3.11.0
+ 3.2.2
+
+ UTF-8
+
+
+
+
+
+ com.google.protobuf
+ protobuf-java
+ ${protobuf.version}
+ compile
+
+
+
+ com.google.api.grpc
+ proto-google-common-protos
+ ${proto-google-common-protos.version}
+ compile
+
+
+
+ org.junit.jupiter
+ junit-jupiter
+ ${junit.version}
+ test
+
+
+
+
+
+
+
+
+ org.apache.maven.plugins
+ maven-compiler-plugin
+ ${maven-compiler-plugin.version}
+
+
+
+ org.apache.maven.plugins
+ maven-surefire-plugin
+ ${maven-surefire-plugin.version}
+
+
+
+ @project.groupId@
+ @project.artifactId@
+ @project.version@
+
+
+ ${protobuf.version}
+
+
+
+
+
+ generate
+
+
+
+
+
+
+
+
diff --git a/src/it/gh-132-duplicate-maven-dependencies/some-dependency-1/pom.xml b/src/it/gh-132-duplicate-maven-dependencies/some-dependency-1/pom.xml
new file mode 100644
index 00000000..35940611
--- /dev/null
+++ b/src/it/gh-132-duplicate-maven-dependencies/some-dependency-1/pom.xml
@@ -0,0 +1,47 @@
+
+
+
+ 4.0.0
+
+
+ org.example
+ some-parent
+ 0.0.1-SNAPSHOT
+ ../pom.xml
+
+
+ some-dependency-1
+
+
+
+ com.google.protobuf
+ protobuf-java
+ compile
+
+
+
+ com.google.api.grpc
+ proto-google-common-protos
+ compile
+
+
+
+
diff --git a/src/it/gh-132-duplicate-maven-dependencies/some-dependency-2/pom.xml b/src/it/gh-132-duplicate-maven-dependencies/some-dependency-2/pom.xml
new file mode 100644
index 00000000..82f975e3
--- /dev/null
+++ b/src/it/gh-132-duplicate-maven-dependencies/some-dependency-2/pom.xml
@@ -0,0 +1,41 @@
+
+
+
+ 4.0.0
+
+
+ org.example
+ some-parent
+ 0.0.1-SNAPSHOT
+ ../pom.xml
+
+
+ some-dependency-2
+
+
+
+ com.google.protobuf
+ protobuf-java
+ compile
+
+
+
+
diff --git a/src/it/gh-132-duplicate-maven-dependencies/some-dependency-3/pom.xml b/src/it/gh-132-duplicate-maven-dependencies/some-dependency-3/pom.xml
new file mode 100644
index 00000000..9350066c
--- /dev/null
+++ b/src/it/gh-132-duplicate-maven-dependencies/some-dependency-3/pom.xml
@@ -0,0 +1,47 @@
+
+
+
+ 4.0.0
+
+
+ org.example
+ some-parent
+ 0.0.1-SNAPSHOT
+ ../pom.xml
+
+
+ some-dependency-3
+
+
+
+ com.google.protobuf
+ protobuf-java
+ compile
+
+
+
+ com.google.api.grpc
+ proto-google-common-protos
+ compile
+
+
+
+
diff --git a/src/it/gh-132-duplicate-maven-dependencies/some-dependency-4/pom.xml b/src/it/gh-132-duplicate-maven-dependencies/some-dependency-4/pom.xml
new file mode 100644
index 00000000..fc584c60
--- /dev/null
+++ b/src/it/gh-132-duplicate-maven-dependencies/some-dependency-4/pom.xml
@@ -0,0 +1,41 @@
+
+
+
+ 4.0.0
+
+
+ org.example
+ some-parent
+ 0.0.1-SNAPSHOT
+ ../pom.xml
+
+
+ some-dependency-4
+
+
+
+ com.google.protobuf
+ protobuf-java
+ compile
+
+
+
+
diff --git a/src/it/gh-132-duplicate-maven-dependencies/some-project/invoker.properties b/src/it/gh-132-duplicate-maven-dependencies/some-project/invoker.properties
new file mode 100644
index 00000000..71cb16da
--- /dev/null
+++ b/src/it/gh-132-duplicate-maven-dependencies/some-project/invoker.properties
@@ -0,0 +1,17 @@
+#
+# Copyright (C) 2023 - 2024, Ashley Scopes.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+invoker.goals = clean package
diff --git a/src/it/gh-132-duplicate-maven-dependencies/some-project/pom.xml b/src/it/gh-132-duplicate-maven-dependencies/some-project/pom.xml
new file mode 100644
index 00000000..3fb4673e
--- /dev/null
+++ b/src/it/gh-132-duplicate-maven-dependencies/some-project/pom.xml
@@ -0,0 +1,106 @@
+
+
+
+ 4.0.0
+
+
+ org.example
+ some-parent
+ 0.0.1-SNAPSHOT
+ ../pom.xml
+
+
+ some-project
+
+
+ 5.10.1
+ 4.26.0
+
+ 3.11.0
+ 3.2.2
+
+ UTF-8
+
+
+
+
+ ${project.parent.groupId}
+ some-dependency-1
+ ${project.parent.version}
+ compile
+
+
+
+ ${project.parent.groupId}
+ some-dependency-2
+ ${project.parent.version}
+ compile
+
+
+
+ ${project.parent.groupId}
+ some-dependency-3
+ ${project.parent.version}
+ compile
+
+
+
+ ${project.parent.groupId}
+ some-dependency-4
+ ${project.parent.version}
+ compile
+
+
+
+ com.google.protobuf
+ protobuf-java
+ compile
+
+
+
+ org.junit.jupiter
+ junit-jupiter
+ test
+
+
+
+
+
+
+ @project.groupId@
+ @project.artifactId@
+ @project.version@
+
+
+ ${protobuf.version}
+
+
+
+
+
+ generate
+
+
+
+
+
+
+
diff --git a/src/it/gh-132-duplicate-maven-dependencies/some-project/src/main/protobuf/helloworld.proto b/src/it/gh-132-duplicate-maven-dependencies/some-project/src/main/protobuf/helloworld.proto
new file mode 100644
index 00000000..8d91946c
--- /dev/null
+++ b/src/it/gh-132-duplicate-maven-dependencies/some-project/src/main/protobuf/helloworld.proto
@@ -0,0 +1,27 @@
+//
+// Copyright (C) 2023 - 2024, Ashley Scopes.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+syntax = "proto3";
+
+option java_multiple_files = true;
+option java_package = "org.example.helloworld";
+
+package org.example.helloworld;
+
+message GreetingRequest {
+ string name = 1;
+}
+
diff --git a/src/it/gh-132-duplicate-maven-dependencies/some-project/src/test/java/org/example/helloworld/ProtobufTest.java b/src/it/gh-132-duplicate-maven-dependencies/some-project/src/test/java/org/example/helloworld/ProtobufTest.java
new file mode 100644
index 00000000..21038f9a
--- /dev/null
+++ b/src/it/gh-132-duplicate-maven-dependencies/some-project/src/test/java/org/example/helloworld/ProtobufTest.java
@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2023 - 2024, Ashley Scopes.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.example.helloworld;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.io.ByteArrayOutputStream;
+import java.util.ArrayList;
+import org.junit.jupiter.api.Test;
+
+class ProtobufTest {
+ @Test
+ void generatedProtobufSourcesAreFullMessages() throws Throwable {
+ // When
+ var superClasses = new ArrayList();
+ Class> superClass = GreetingRequest.class;
+
+ do {
+ superClasses.add(superClass.getName());
+ superClass = superClass.getSuperclass();
+ } while (superClass != null);
+
+ // Then
+ // GeneratedMessageV3 for protobuf-java 3.25.3 and older.
+ // GeneratedMessage for protobuf-java 4.26.0 and newer.
+ assertTrue(superClasses.contains("com.google.protobuf.GeneratedMessage"));
+ }
+
+ @Test
+ void generatedProtobufSourcesAreValid() throws Throwable {
+ // Given
+ var expectedGreetingRequest = GreetingRequest
+ .newBuilder()
+ .setName("Ashley")
+ .build();
+
+ // When
+ var baos = new ByteArrayOutputStream();
+ expectedGreetingRequest.writeTo(baos);
+ var actualGreetingRequest = GreetingRequest.parseFrom(baos.toByteArray());
+
+ assertNotEquals(0, baos.toByteArray().length);
+
+ // Then
+ assertEquals(expectedGreetingRequest.getName(), actualGreetingRequest.getName());
+ }
+}
diff --git a/src/main/java/io/github/ascopes/protobufmavenplugin/source/ProtoSourceResolver.java b/src/main/java/io/github/ascopes/protobufmavenplugin/source/ProtoSourceResolver.java
index ca7d4880..2b454643 100644
--- a/src/main/java/io/github/ascopes/protobufmavenplugin/source/ProtoSourceResolver.java
+++ b/src/main/java/io/github/ascopes/protobufmavenplugin/source/ProtoSourceResolver.java
@@ -18,6 +18,8 @@
import static java.util.function.Predicate.not;
+import io.github.ascopes.protobufmavenplugin.platform.FileUtils;
+import io.github.ascopes.protobufmavenplugin.platform.HostSystem;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
@@ -115,6 +117,11 @@ public Collection createProtoFileListings(
originalPaths
.stream()
+ // GH-132: Normalize to ensure different paths to the same file do not
+ // get duplicated across more than one extraction site.
+ .map(FileUtils::normalize)
+ // GH-132: Avoid running multiple times on the same location.
+ .distinct()
.map(this::submitProtoFileListingTask)
// terminal operation to ensure all are scheduled prior to joining.
.collect(Collectors.toList())