Produce a single library for multiple file dependencies on the same file

Previously, the Gradle plugin’s ProjectLibraries produced a new library
for every file dependency, even if the dependencies where on the same
file. This would lead to a repackaging failure due to multiple
libraries having the same name.

This commit updates ProjectLibraries to treat file dependencies on the
same file as a single library, thereby resolving the name clash.

Fixes gh-1646

spring-boot-integration-tests/src/test/java/org/springframework/boot/gradle/MultiProjectRepackagingTests.java

@@ -17,11 +17,9 @@
 package org.springframework.boot.gradle;
 
 import java.io.File;
-import java.io.IOException;
 import java.util.jar.JarFile;
 
 import org.gradle.tooling.ProjectConnection;
-import org.junit.BeforeClass;
 import org.junit.Test;
 import org.springframework.boot.dependency.tools.ManagedDependencies;
 
@@ -38,21 +36,31 @@ public class MultiProjectRepackagingTests {
 	private static final String BOOT_VERSION = ManagedDependencies.get()
 			.find("spring-boot").getVersion();
 
-	private static ProjectConnection project;
-
-	@BeforeClass
-	public static void createProject() throws IOException {
-		project = new ProjectCreator().createProject("multi-project-repackage");
-	}
-
 	@Test
 	public void repackageWithTransitiveFileDependency() throws Exception {
+		ProjectConnection project = new ProjectCreator()
+				.createProject("multi-project-transitive-file-dependency");
 		project.newBuild().forTasks("clean", "build")
-				.withArguments("-PbootVersion=" + BOOT_VERSION, "-Prepackage=true").run();
-		File buildLibs = new File("target/multi-project-repackage/main/build/libs");
+				.withArguments("-PbootVersion=" + BOOT_VERSION).run();
+		File buildLibs = new File(
+				"target/multi-project-transitive-file-dependency/main/build/libs");
 		JarFile jarFile = new JarFile(new File(buildLibs, "main.jar"));
 		assertThat(jarFile.getEntry("lib/commons-logging-1.1.3.jar"), notNullValue());
 		assertThat(jarFile.getEntry("lib/foo.jar"), notNullValue());
 		jarFile.close();
 	}
+
+	@Test
+	public void repackageWithCommonFileDependency() throws Exception {
+		ProjectConnection project = new ProjectCreator()
+				.createProject("multi-project-common-file-dependency");
+		project.newBuild().forTasks("clean", "build")
+				.withArguments("-PbootVersion=" + BOOT_VERSION).run();
+		File buildLibs = new File(
+				"target/multi-project-common-file-dependency/build/libs");
+		JarFile jarFile = new JarFile(new File(buildLibs,
+				"multi-project-common-file-dependency.jar"));
+		assertThat(jarFile.getEntry("lib/foo.jar"), notNullValue());
+		jarFile.close();
+	}
 }

spring-boot-integration-tests/src/test/resources/multi-project-common-file-dependency/build.gradle

@@ -0,0 +1,28 @@
+buildscript {
+	repositories {
+		mavenLocal()
+	}
+	dependencies {
+		classpath "org.springframework.boot:spring-boot-gradle-plugin:${project.bootVersion}"
+	}
+}
+
+subprojects {
+	apply plugin: 'java'
+
+	dependencies {
+		compile rootProject.files {'lib/foo.jar'}
+	}
+}
+
+apply plugin: 'spring-boot'
+
+springBoot {
+	mainClass = 'foo.bar.Baz'
+}
+
+dependencies {
+	compile project(':one')
+	compile project(':two')
+}
+

spring-boot-integration-tests/src/test/resources/multi-project-common-file-dependency/settings.gradle

@@ -0,0 +1,3 @@
+
+include 'one'
+include 'two'

spring-boot-tools/spring-boot-gradle-plugin/src/main/groovy/org/springframework/boot/gradle/repackage/ProjectLibraries.java

@@ -199,6 +199,23 @@ class ProjectLibraries implements Libraries {
 			return name;
 		}
 
+		@Override
+		public int hashCode() {
+			return getFile().hashCode();
+		}
+
+		@Override
+		public boolean equals(Object obj) {
+			if (obj instanceof GradleLibrary) {
+				return getFile().equals(((GradleLibrary) obj).getFile());
+			}
+			return false;
+		}
+
+		@Override
+		public String toString() {
+			return getFile().getAbsolutePath();
+		}
 	}
 
 	/**