Add explicit DuplicatesStrategy as required by gradle 7+ (#470)

src/main/groovy/com/google/protobuf/gradle/ProtobufExtract.groovy

@@ -33,6 +33,7 @@ import com.google.common.base.Preconditions
 import groovy.transform.CompileDynamic
 import org.gradle.api.DefaultTask
 import org.gradle.api.file.ConfigurableFileCollection
+import org.gradle.api.file.DuplicatesStrategy
 import org.gradle.api.file.FileCollection
 import org.gradle.api.file.FileSystemLocation
 import org.gradle.api.file.FileTree
@@ -113,6 +114,8 @@ abstract class ProtobufExtract extends DefaultTask {
       spec.from(allProtoFiles)
       spec.include('**/*.proto')
       spec.into(destDir)
+      // gradle 7+ requires a duplicate strategy to be explicitly defined
+      spec.duplicatesStrategy = DuplicatesStrategy.INCLUDE
     }
   }
 

src/test/groovy/com/google/protobuf/gradle/ProtobufKotlinDslCopySpecTest.groovy

@@ -0,0 +1,55 @@
+package com.google.protobuf.gradle
+
+import groovy.transform.CompileDynamic
+import org.gradle.testkit.runner.BuildResult
+import org.gradle.testkit.runner.GradleRunner
+import org.gradle.testkit.runner.TaskOutcome
+import spock.lang.Specification
+import spock.lang.Unroll
+
+/**
+ * Unit test confirming copy spec is explicitly defined for gradle7+ compliance.
+ */
+@CompileDynamic
+class ProtobufKotlinDslCopySpecTest extends Specification {
+  private static final List<String> GRADLE_VERSIONS = ["5.6", "6.0", "6.7.1", "7.0"]
+
+  @Unroll
+  void "testProjectKotlinDslCopySpec should declare explicit copy spec [gradle #gradleVersion]"() {
+    given: "project from testProjectKotlinDslCopySpec"
+    File projectDir = ProtobufPluginTestHelper.projectBuilder('testProjectKotlinDslCopySpec')
+            .copyDirs('testProjectKotlinDslCopySpec')
+            .build()
+
+    when: "build is invoked"
+    BuildResult result = GradleRunner.create()
+            .withProjectDir(projectDir)
+            .withArguments('test', 'build', '--stacktrace')
+            .withPluginClasspath()
+            .withGradleVersion(gradleVersion)
+            .forwardStdOutput(new OutputStreamWriter(System.out))
+            .forwardStdError(new OutputStreamWriter(System.err))
+            .build()
+
+    then: "it succeed"
+
+    result.task(":test").outcome == TaskOutcome.SUCCESS
+
+    verifyProjectDir(projectDir)
+
+    where:
+    gradleVersion << GRADLE_VERSIONS
+  }
+
+  private static void verifyProjectDir(File projectDir) {
+    File generatedSrcDir = new File(projectDir.path, "build/generated/source/proto/main/java")
+    List<File> fileList = []
+    generatedSrcDir.eachFileRecurse { file ->
+      if (file.path.endsWith('.java')) {
+        fileList.add (file)
+      }
+    }
+    assert fileList.size > 0
+  }
+
+}

testProjectBase/build_base.gradle

@@ -29,10 +29,10 @@ dependencies {
   protobuf files("ext/")
   testProtobuf files("lib/protos-test.tar.gz")
 
-  compile protobufDep
-  testCompile 'junit:junit:4.12'
+  implementation protobufDep
+  testImplementation 'junit:junit:4.12'
   // KotlinFooTest.kt requires reflection utilities
-  testCompile "org.jetbrains.kotlin:kotlin-reflect:1.2.0"
+  testImplementation "org.jetbrains.kotlin:kotlin-reflect:1.2.0"
   grpcCompile protobufDep
   grpcCompile 'io.grpc:grpc-stub:1.0.0-pre2'
   grpcCompile 'io.grpc:grpc-protobuf:1.0.0-pre2'

testProjectDependent/build.gradle

@@ -14,10 +14,10 @@ repositories {
 }
 
 dependencies {
-    compile 'com.google.protobuf:protobuf-java:3.0.0'
-    compile project(':testProject')
+    implementation 'com.google.protobuf:protobuf-java:3.0.0'
+    implementation project(':testProject')
 
-    testCompile 'junit:junit:4.12'
+    testImplementation 'junit:junit:4.12'
 }
 
 protobuf.protoc {

testProjectKotlinDslCopySpec/build.gradle.kts

@@ -0,0 +1,59 @@
+import com.google.protobuf.gradle.generateProtoTasks
+import com.google.protobuf.gradle.id
+import com.google.protobuf.gradle.ofSourceSet
+import com.google.protobuf.gradle.plugins
+import com.google.protobuf.gradle.protobuf
+import com.google.protobuf.gradle.protoc
+
+plugins {
+  java
+  id("java-library")
+  id("com.google.protobuf").version("0.8.15")
+}
+
+repositories {
+  maven("https://plugins.gradle.org/m2/")
+}
+
+java {
+  sourceCompatibility = JavaVersion.VERSION_1_8
+  targetCompatibility = JavaVersion.VERSION_1_8
+}
+
+val protobufDepVersion = "3.0.0"
+val grpcVersion = "1.37.0"
+
+dependencies {
+  implementation("io.grpc:grpc-protobuf:$grpcVersion")
+  implementation("io.grpc:grpc-stub:$grpcVersion")
+  implementation("com.google.protobuf:protobuf-java:$protobufDepVersion")
+  testImplementation("org.junit.jupiter:junit-jupiter-api:5.7.1")
+  testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine:5.7.1")
+}
+
+
+protobuf {
+  protoc {
+    artifact = "com.google.protobuf:protoc:$protobufDepVersion"
+  }
+  plugins {
+    id("grpc") {
+      artifact = "io.grpc:protoc-gen-grpc-java:$grpcVersion"
+    }
+  }
+  generateProtoTasks {
+    ofSourceSet("main").forEach {
+      it.plugins {
+        id("grpc") {
+          outputSubDir = "grpc"
+        }
+      }
+    }
+  }
+}
+tasks {
+  test {
+    useJUnitPlatform {
+    }
+  }
+}

testProjectKotlinDslCopySpec/settings.gradle.kts

@@ -0,0 +1,8 @@
+pluginManagement {
+
+    repositories {
+        gradlePluginPortal()
+        google()
+    }
+}
+

testProjectKotlinDslCopySpec/src/main/proto/google/type/money.proto

@@ -0,0 +1,42 @@
+// Copyright 2020 Google LLC
+//
+// 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";
+
+package google.type;
+
+option cc_enable_arenas = true;
+option go_package = "google.golang.org/genproto/googleapis/type/money;money";
+option java_multiple_files = true;
+option java_outer_classname = "MoneyProto";
+option java_package = "com.google.type";
+option objc_class_prefix = "GTP";
+
+// Represents an amount of money with its currency type.
+message Money {
+  // The three-letter currency code defined in ISO 4217.
+  string currency_code = 1;
+
+  // The whole units of the amount.
+  // For example if `currencyCode` is `"USD"`, then 1 unit is one US dollar.
+  int64 units = 2;
+
+  // Number of nano (10^-9) units of the amount.
+  // The value must be between -999,999,999 and +999,999,999 inclusive.
+  // If `units` is positive, `nanos` must be positive or zero.
+  // If `units` is zero, `nanos` can be positive, zero, or negative.
+  // If `units` is negative, `nanos` must be negative or zero.
+  // For example $-1.75 is represented as `units`=-1 and `nanos`=-750,000,000.
+  int32 nanos = 3;
+}

testProjectKotlinDslCopySpec/src/test/java/com/myapp/ExampleUnitTest.java

@@ -0,0 +1,12 @@
+package com.myapp;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class ExampleUnitTest {
+
+  @Test
+  public void addition_isCorrect() {
+    Assertions.assertEquals(4, 2 + 2);
+  }
+}