Add support for dependency exclusions

Closes gh-906

initializr-generator/src/main/java/io/spring/initializr/generator/buildsystem/Dependency.java

@@ -16,12 +16,19 @@
 
 package io.spring.initializr.generator.buildsystem;
 
+import java.util.Collections;
+import java.util.Objects;
+import java.util.Set;
+
 import io.spring.initializr.generator.version.VersionReference;
 
+import org.springframework.util.Assert;
+
 /**
  * A dependency to be declared in a project's build configuration.
  *
  * @author Andy Wilkinson
+ * @author Stephane Nicoll
  */
 public class Dependency {
 
@@ -35,6 +42,8 @@ public class Dependency {
 
 	private final String type;
 
+	private final Set<Exclusion> exclusions;
+
 	public Dependency(String groupId, String artifactId) {
 		this(groupId, artifactId, DependencyScope.COMPILE);
 	}
@@ -50,11 +59,17 @@ public class Dependency {
 
 	public Dependency(String groupId, String artifactId, VersionReference version,
 			DependencyScope scope, String type) {
+		this(groupId, artifactId, version, scope, type, null);
+	}
+
+	public Dependency(String groupId, String artifactId, VersionReference version,
+			DependencyScope scope, String type, Set<Exclusion> exclusions) {
 		this.groupId = groupId;
 		this.artifactId = artifactId;
 		this.version = version;
 		this.scope = scope;
 		this.type = type;
+		this.exclusions = (exclusions != null) ? exclusions : Collections.emptySet();
 	}
 
 	/**
@@ -99,4 +114,56 @@ public class Dependency {
 		return this.type;
 	}
 
+	/**
+	 * The {@link Exclusion exclusions} to apply.
+	 * @return the exclusions to apply
+	 */
+	public Set<Exclusion> getExclusions() {
+		return this.exclusions;
+	}
+
+	/**
+	 * Define the reference to a transitive dependency to exclude.
+	 */
+	public static final class Exclusion {
+
+		private final String groupId;
+
+		private final String artifactId;
+
+		public Exclusion(String groupId, String artifactId) {
+			Assert.hasText(groupId, "GroupId must not be null");
+			Assert.hasText(groupId, "ArtifactId must not be null");
+			this.groupId = groupId;
+			this.artifactId = artifactId;
+		}
+
+		public String getGroupId() {
+			return this.groupId;
+		}
+
+		public String getArtifactId() {
+			return this.artifactId;
+		}
+
+		@Override
+		public boolean equals(Object o) {
+			if (this == o) {
+				return true;
+			}
+			if (o == null || getClass() != o.getClass()) {
+				return false;
+			}
+			Exclusion exclusion = (Exclusion) o;
+			return this.groupId.equals(exclusion.groupId)
+					&& this.artifactId.equals(exclusion.artifactId);
+		}
+
+		@Override
+		public int hashCode() {
+			return Objects.hash(this.groupId, this.artifactId);
+		}
+
+	}
+
 }

initializr-generator/src/main/java/io/spring/initializr/generator/buildsystem/DependencyContainer.java

@@ -16,9 +16,12 @@
 
 package io.spring.initializr.generator.buildsystem;
 
+import java.util.Arrays;
 import java.util.LinkedHashMap;
+import java.util.LinkedHashSet;
 import java.util.function.Function;
 
+import io.spring.initializr.generator.buildsystem.Dependency.Exclusion;
 import io.spring.initializr.generator.version.VersionReference;
 
 /**
@@ -72,4 +75,22 @@ public class DependencyContainer extends BuildItemContainer<String, Dependency>
 		add(id, new Dependency(groupId, artifactId, version, scope, type));
 	}
 
+	/**
+	 * Register a {@link Dependency} with the specified {@code id}, version,
+	 * {@link DependencyScope scope}, type and exclusions.
+	 * @param id the id of the dependency
+	 * @param groupId the groupId
+	 * @param artifactId the artifactId
+	 * @param version the {@link VersionReference}
+	 * @param scope the {@link DependencyScope}
+	 * @param type the artifact type
+	 * @param exclusions the exclusion(s) to apply
+	 */
+	public void add(String id, String groupId, String artifactId,
+			VersionReference version, DependencyScope scope, String type,
+			Exclusion... exclusions) {
+		add(id, new Dependency(groupId, artifactId, version, scope, type,
+				new LinkedHashSet<>(Arrays.asList(exclusions))));
+	}
+
 }

initializr-generator/src/main/java/io/spring/initializr/generator/buildsystem/gradle/GradleBuildWriter.java

@@ -145,11 +145,17 @@ public abstract class GradleBuildWriter {
 				.addAll(filterDependencies(dependencies, DependencyScope.TEST_COMPILE));
 		sortedDependencies
 				.addAll(filterDependencies(dependencies, DependencyScope.TEST_RUNTIME));
-		writeNestedCollection(writer, "dependencies", sortedDependencies,
-				this::dependencyAsString, writer::println);
+		if (!sortedDependencies.isEmpty()) {
+			writer.println();
+			writer.println("dependencies" + " {");
+			writer.indented(() -> sortedDependencies
+					.forEach((dependency) -> writeDependency(writer, dependency)));
+			writer.println("}");
+		}
 	}
 
-	protected abstract String dependencyAsString(Dependency dependency);
+	protected abstract void writeDependency(IndentingWriter writer,
+			Dependency dependency);
 
 	protected String configurationForScope(DependencyScope type) {
 		switch (type) {
@@ -228,8 +234,8 @@ public abstract class GradleBuildWriter {
 		}
 	}
 
-	private <T> void writeCollection(IndentingWriter writer, Collection<T> collection,
-			Function<T, String> converter) {
+	protected final <T> void writeCollection(IndentingWriter writer,
+			Collection<T> collection, Function<T, String> converter) {
 		writeCollection(writer, collection, converter, null);
 	}
 

initializr-generator/src/main/java/io/spring/initializr/generator/buildsystem/gradle/GroovyDslGradleBuildWriter.java

@@ -22,6 +22,7 @@ import java.util.function.BiFunction;
 
 import io.spring.initializr.generator.buildsystem.BillOfMaterials;
 import io.spring.initializr.generator.buildsystem.Dependency;
+import io.spring.initializr.generator.buildsystem.Dependency.Exclusion;
 import io.spring.initializr.generator.buildsystem.MavenRepository;
 import io.spring.initializr.generator.io.IndentingWriter;
 import io.spring.initializr.generator.version.VersionProperty;
@@ -124,14 +125,30 @@ public class GroovyDslGradleBuildWriter extends GradleBuildWriter {
 	}
 
 	@Override
-	protected String dependencyAsString(Dependency dependency) {
+	protected void writeDependency(IndentingWriter writer, Dependency dependency) {
 		String quoteStyle = determineQuoteStyle(dependency.getVersion());
 		String version = determineVersion(dependency.getVersion());
 		String type = dependency.getType();
-		return configurationForScope(dependency.getScope()) + " " + quoteStyle
-				+ dependency.getGroupId() + ":" + dependency.getArtifactId()
-				+ ((version != null) ? ":" + version : "")
-				+ ((type != null) ? "@" + type : "") + quoteStyle;
+		boolean hasExclusions = !dependency.getExclusions().isEmpty();
+		writer.print(configurationForScope(dependency.getScope()));
+		writer.print((hasExclusions) ? "(" : " ");
+		writer.print(quoteStyle + dependency.getGroupId() + ":"
+				+ dependency.getArtifactId() + ((version != null) ? ":" + version : "")
+				+ ((type != null) ? "@" + type : "") + quoteStyle);
+		if (hasExclusions) {
+			writer.println(") {");
+			writer.indented(() -> writeCollection(writer, dependency.getExclusions(),
+					this::dependencyExclusionAsString));
+			writer.println("}");
+		}
+		else {
+			writer.println();
+		}
+	}
+
+	private String dependencyExclusionAsString(Exclusion exclusion) {
+		return "exclude group: '" + exclusion.getGroupId() + "', module: '"
+				+ exclusion.getArtifactId() + "'";
 	}
 
 	private String determineQuoteStyle(VersionReference versionReference) {

initializr-generator/src/main/java/io/spring/initializr/generator/buildsystem/gradle/KotlinDslGradleBuildWriter.java

@@ -23,6 +23,7 @@ import java.util.stream.Collectors;
 
 import io.spring.initializr.generator.buildsystem.BillOfMaterials;
 import io.spring.initializr.generator.buildsystem.Dependency;
+import io.spring.initializr.generator.buildsystem.Dependency.Exclusion;
 import io.spring.initializr.generator.buildsystem.MavenRepository;
 import io.spring.initializr.generator.buildsystem.gradle.GradleBuild.ConfigurationCustomization;
 import io.spring.initializr.generator.buildsystem.gradle.GradleBuild.TaskCustomization;
@@ -131,13 +132,27 @@ public class KotlinDslGradleBuildWriter extends GradleBuildWriter {
 	}
 
 	@Override
-	protected String dependencyAsString(Dependency dependency) {
+	protected void writeDependency(IndentingWriter writer, Dependency dependency) {
 		String version = determineVersion(dependency.getVersion());
 		String type = dependency.getType();
-		return configurationForScope(dependency.getScope()) + "(\""
+		writer.print(configurationForScope(dependency.getScope()) + "(\""
 				+ dependency.getGroupId() + ":" + dependency.getArtifactId()
 				+ ((version != null) ? ":" + version : "")
-				+ ((type != null) ? "@" + type : "") + "\")";
+				+ ((type != null) ? "@" + type : "") + "\")");
+		if (!dependency.getExclusions().isEmpty()) {
+			writer.println(" {");
+			writer.indented(() -> writeCollection(writer, dependency.getExclusions(),
+					this::dependencyExclusionAsString));
+			writer.println("}");
+		}
+		else {
+			writer.println();
+		}
+	}
+
+	private String dependencyExclusionAsString(Exclusion exclusion) {
+		return "exclude(group = \"" + exclusion.getGroupId() + "\", module = \""
+				+ exclusion.getArtifactId() + "\")";
 	}
 
 	@Override

initializr-generator/src/main/java/io/spring/initializr/generator/buildsystem/maven/MavenBuildWriter.java

@@ -27,6 +27,7 @@ import java.util.stream.Stream;
 
 import io.spring.initializr.generator.buildsystem.BillOfMaterials;
 import io.spring.initializr.generator.buildsystem.Dependency;
+import io.spring.initializr.generator.buildsystem.Dependency.Exclusion;
 import io.spring.initializr.generator.buildsystem.DependencyComparator;
 import io.spring.initializr.generator.buildsystem.DependencyContainer;
 import io.spring.initializr.generator.buildsystem.DependencyScope;
@@ -158,6 +159,17 @@ public class MavenBuildWriter {
 				writeSingleElement(writer, "optional", Boolean.toString(true));
 			}
 			writeSingleElement(writer, "type", dependency.getType());
+			if (!dependency.getExclusions().isEmpty()) {
+				writeElement(writer, "exclusions", () -> writeCollection(writer,
+						dependency.getExclusions(), this::writeDependencyExclusion));
+			}
+		});
+	}
+
+	private void writeDependencyExclusion(IndentingWriter writer, Exclusion exclusion) {
+		writeElement(writer, "exclusion", () -> {
+			writeSingleElement(writer, "groupId", exclusion.getGroupId());
+			writeSingleElement(writer, "artifactId", exclusion.getArtifactId());
 		});
 	}
 

initializr-generator/src/test/java/io/spring/initializr/generator/buildsystem/gradle/GroovyDslGradleBuildWriterTests.java

@@ -20,6 +20,7 @@ import java.io.IOException;
 import java.io.StringWriter;
 import java.util.List;
 
+import io.spring.initializr.generator.buildsystem.Dependency.Exclusion;
 import io.spring.initializr.generator.buildsystem.DependencyScope;
 import io.spring.initializr.generator.io.IndentingWriter;
 import io.spring.initializr.generator.test.io.TextTestUtils;
@@ -389,6 +390,21 @@ class GroovyDslGradleBuildWriterTests {
 				"}");
 	}
 
+	@Test
+	void gradleBuildWithExclusions() throws IOException {
+		GradleBuild build = new GradleBuild();
+		build.dependencies().add("test", "com.example", "test", null,
+				DependencyScope.COMPILE, null,
+				new Exclusion("com.example.legacy", "legacy-one"),
+				new Exclusion("com.example.another", "legacy-two"));
+		List<String> lines = generateBuild(build);
+		assertThat(lines).containsSequence("dependencies {",
+				"    implementation('com.example:test') {",
+				"        exclude group: 'com.example.legacy', module: 'legacy-one'",
+				"        exclude group: 'com.example.another', module: 'legacy-two'",
+				"    }", "}");
+	}
+
 	@Test
 	void gradleBuildWithNonNullArtifactTypeDependency() throws IOException {
 		GradleBuild build = new GradleBuild();

initializr-generator/src/test/java/io/spring/initializr/generator/buildsystem/gradle/KotlinDslGradleBuildWriterTests.java

@@ -20,6 +20,7 @@ import java.io.IOException;
 import java.io.StringWriter;
 import java.util.List;
 
+import io.spring.initializr.generator.buildsystem.Dependency.Exclusion;
 import io.spring.initializr.generator.buildsystem.DependencyScope;
 import io.spring.initializr.generator.io.IndentingWriter;
 import io.spring.initializr.generator.test.io.TextTestUtils;
@@ -393,6 +394,21 @@ class KotlinDslGradleBuildWriterTests {
 				"}");
 	}
 
+	@Test
+	void gradleBuildWithExclusions() throws IOException {
+		GradleBuild build = new GradleBuild();
+		build.dependencies().add("test", "com.example", "test", null,
+				DependencyScope.COMPILE, null,
+				new Exclusion("com.example.legacy", "legacy-one"),
+				new Exclusion("com.example.another", "legacy-two"));
+		List<String> lines = generateBuild(build);
+		assertThat(lines).containsSequence("dependencies {",
+				"    implementation(\"com.example:test\") {",
+				"        exclude(group = \"com.example.legacy\", module = \"legacy-one\")",
+				"        exclude(group = \"com.example.another\", module = \"legacy-two\")",
+				"    }", "}");
+	}
+
 	@Test
 	void gradleBuildWithNonNullArtifactTypeDependency() throws IOException {
 		GradleBuild build = new GradleBuild();

initializr-generator/src/test/java/io/spring/initializr/generator/buildsystem/maven/MavenBuildWriterTests.java

@@ -19,6 +19,7 @@ package io.spring.initializr.generator.buildsystem.maven;
 import java.io.StringWriter;
 import java.util.function.Consumer;
 
+import io.spring.initializr.generator.buildsystem.Dependency.Exclusion;
 import io.spring.initializr.generator.buildsystem.DependencyScope;
 import io.spring.initializr.generator.io.IndentingWriter;
 import io.spring.initializr.generator.test.assertj.NodeAssert;
@@ -255,6 +256,35 @@ class MavenBuildWriterTests {
 		});
 	}
 
+	@Test
+	void pomWithExclusions() throws Exception {
+		MavenBuild build = new MavenBuild();
+		build.setGroup("com.example.demo");
+		build.setArtifact("demo");
+		build.dependencies().add("test", "com.example", "test", null,
+				DependencyScope.COMPILE, null,
+				new Exclusion("com.example.legacy", "legacy-one"),
+				new Exclusion("com.example.another", "legacy-two"));
+		generatePom(build, (pom) -> {
+			NodeAssert dependency = pom.nodeAtPath("/project/dependencies/dependency");
+			assertThat(dependency).textAtPath("groupId").isEqualTo("com.example");
+			assertThat(dependency).textAtPath("artifactId").isEqualTo("test");
+			assertThat(dependency).textAtPath("version").isNullOrEmpty();
+			assertThat(dependency).textAtPath("scope").isNullOrEmpty();
+			assertThat(dependency).textAtPath("optional").isNullOrEmpty();
+			NodeAssert exclusions = assertThat(dependency).nodeAtPath("exclusions");
+			NodeAssert firstExclusion = assertThat(exclusions).nodeAtPath("exclusion[1]");
+			assertThat(firstExclusion).textAtPath("groupId")
+					.isEqualTo("com.example.legacy");
+			assertThat(firstExclusion).textAtPath("artifactId").isEqualTo("legacy-one");
+			NodeAssert secondExclusion = assertThat(exclusions)
+					.nodeAtPath("exclusion[2]");
+			assertThat(secondExclusion).textAtPath("groupId")
+					.isEqualTo("com.example.another");
+			assertThat(secondExclusion).textAtPath("artifactId").isEqualTo("legacy-two");
+		});
+	}
+
 	@Test
 	void pomWithNonNullArtifactTypeDependency() throws Exception {
 		MavenBuild build = new MavenBuild();