Add getAdditionalEntries to IClasspathContributor

Adds a new method to allow classpath contributor to append additional
classpath entries at the end of the calculation process.

Author: steffenschmitt1

org.eclipse.pde.doc.user/forceQualifierUpdate.txt

@@ -1 +1,2 @@
-Added new method to IBuildEntry
+Added new method to IBuildEntry
+https://github.com/eclipse-pde/eclipse.pde/issues/1846

ui/org.eclipse.pde.core/src/org/eclipse/pde/core/IClasspathContributor2.java

@@ -0,0 +1,49 @@
+/*******************************************************************************
+ * Copyright (c) 2025 Vector Informatik GmbH and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ *******************************************************************************/
+package org.eclipse.pde.core;
+
+import java.util.stream.Stream;
+
+import org.eclipse.jdt.core.IClasspathEntry;
+import org.eclipse.osgi.service.resolver.BundleDescription;
+import org.eclipse.pde.core.plugin.PluginRegistry;
+import org.osgi.resource.Resource;
+
+/**
+ * Extension interface for {@link org.eclipse.pde.core.IClasspathContributor}.
+ * <p>
+ * This interface allows adding classpath entries after the classpath has been
+ * calculated.
+ * </p>
+ *
+ * @since 3.21
+ */
+public interface IClasspathContributor2 extends IClasspathContributor {
+
+	/**
+	 * Get any additional classpath entries to add to a project when its
+	 * classpath is first computed. The provided {@link BundleDescription}
+	 * describes the plug-in project that the classpath is being computed for.
+	 * The entries are added at the end of the calculation process. Additional
+	 * PDE model information can be obtained using
+	 * {@link PluginRegistry#findModel(Resource)}.
+	 *
+	 * @param project
+	 *            the bundle descriptor for the plug-in project having its
+	 *            classpath computed
+	 * @return additional classpath entries to add to the project at the end of
+	 *         the classpath calculation, possibly empty, must not be
+	 *         <code>null</code>
+	 * @since 3.21
+	 */
+	Stream<IClasspathEntry> getAdditionalEntries(BundleDescription project);
+}

ui/org.eclipse.pde.core/src/org/eclipse/pde/internal/core/RequiredPluginsClasspathContainer.java

@@ -53,6 +53,7 @@
 import org.eclipse.osgi.service.resolver.ImportPackageSpecification;
 import org.eclipse.osgi.service.resolver.StateHelper;
 import org.eclipse.pde.core.IClasspathContributor;
+import org.eclipse.pde.core.IClasspathContributor2;
 import org.eclipse.pde.core.build.IBuild;
 import org.eclipse.pde.core.build.IBuildEntry;
 import org.eclipse.pde.core.build.IBuildModel;
@@ -285,6 +286,11 @@ private List<IClasspathEntry> computePluginEntriesByModel() throws CoreException
 			addJunit5RuntimeDependencies(added, entries);
 			addImplicitDependencies(desc, added, entries);
 
+			// Add any additional library entries contributed via classpath
+			// contributor
+			entries.addAll(getClasspathContributors().filter(IClasspathContributor2.class::isInstance)
+					.map(IClasspathContributor2.class::cast).flatMap(cc -> cc.getAdditionalEntries(desc)).toList());
+
 		return entries;
 	}