Fixes #29298 : Add support for artifact classifiers in BOM generation

Author: chrisdennis

buildSrc/src/main/java/org/springframework/boot/build/bom/BomExtension.java

@@ -316,7 +316,7 @@ public Object methodMissing(String name, Object args) {
 						closure.setResolveStrategy(Closure.DELEGATE_FIRST);
 						closure.setDelegate(moduleHandler);
 						closure.call(moduleHandler);
-						return new Module(name, moduleHandler.type, moduleHandler.exclusions);
+						return new Module(name, moduleHandler.type, moduleHandler.classifier, moduleHandler.exclusions);
 					}
 				}
 				throw new InvalidUserDataException("Invalid configuration for module '" + name + "'");
@@ -328,6 +328,8 @@ public class ModuleHandler {
 
 				private String type;
 
+				private String classifier;
+
 				public void exclude(Map<String, String> exclusion) {
 					this.exclusions.add(new Exclusion(exclusion.get("group"), exclusion.get("module")));
 				}
@@ -336,6 +338,10 @@ public void setType(String type) {
 					this.type = type;
 				}
 
+				public void setClassifier(String classifier) {
+					this.classifier = classifier;
+				}
+
 			}
 
 		}

buildSrc/src/main/java/org/springframework/boot/build/bom/BomPlugin.java

@@ -112,6 +112,7 @@ private void customizePom(MavenPom pom) {
 					replaceVersionsWithVersionPropertyReferences(dependencyManagement);
 					addExclusionsToManagedDependencies(dependencyManagement);
 					addTypesToManagedDependencies(dependencyManagement);
+					addClassifiersToManagedDependencies(dependencyManagement);
 				}
 				else {
 					projectNode.children().add(properties);
@@ -188,6 +189,30 @@ private void addTypesToManagedDependencies(Node dependencyManagement) {
 			}
 		}
 
+		private void addClassifiersToManagedDependencies(Node dependencyManagement) {
+			Node dependencies = findChild(dependencyManagement, "dependencies");
+			if (dependencies != null) {
+				for (Node dependency : findChildren(dependencies, "dependency")) {
+					String groupId = findChild(dependency, "groupId").text();
+					String artifactId = findChild(dependency, "artifactId").text();
+					Set<String> classifiers = this.bom.getLibraries().stream()
+							.flatMap((library) -> library.getGroups().stream())
+							.filter((group) -> group.getId().equals(groupId))
+							.flatMap((group) -> group.getModules().stream())
+							.filter((module) -> module.getName().equals(artifactId)).map(Module::getClassifier)
+							.filter(Objects::nonNull).collect(Collectors.toSet());
+					if (classifiers.size() > 1) {
+						throw new IllegalStateException(
+								"Multiple classifiers for " + groupId + ":" + artifactId + ": " + classifiers);
+					}
+					if (classifiers.size() == 1) {
+						String classifier = classifiers.iterator().next();
+						dependency.appendNode("classifier", classifier);
+					}
+				}
+			}
+		}
+
 		private void addPluginManagement(Node projectNode) {
 			for (Library library : this.bom.getLibraries()) {
 				for (Group group : library.getGroups()) {

buildSrc/src/main/java/org/springframework/boot/build/bom/Library.java

@@ -189,6 +189,8 @@ public static class Module {
 
 		private final String type;
 
+		private final String classifier;
+
 		private final List<Exclusion> exclusions;
 
 		public Module(String name) {
@@ -204,8 +206,13 @@ public Module(String name, List<Exclusion> exclusions) {
 		}
 
 		public Module(String name, String type, List<Exclusion> exclusions) {
+			this(name, type, null, exclusions);
+		}
+
+		public Module(String name, String type, String classifier, List<Exclusion> exclusions) {
 			this.name = name;
 			this.type = type;
+			this.classifier = classifier;
 			this.exclusions = exclusions;
 		}
 
@@ -217,6 +224,10 @@ public String getType() {
 			return this.type;
 		}
 
+		public String getClassifier() {
+			return this.classifier;
+		}
+
 		public List<Exclusion> getExclusions() {
 			return this.exclusions;
 		}