Add option to include all configured sources in ApiFileGenerationMojo

Currently APIFileGenerator scans all folders from the root, but one can
configured folders that are relative to the project, this is then not
discovered.

This adds a new option <addSourceFolders> that when used automatically
adds all configured source folders as extraSourceLocations.

tycho-apitools-plugin/src/main/java/org/eclipse/tycho/apitools/ApiFileGenerationMojo.java

@@ -13,7 +13,10 @@
 package org.eclipse.tycho.apitools;
 
 import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
 import java.util.List;
+import java.util.Map;
 import java.util.Optional;
 import java.util.jar.JarFile;
 import java.util.stream.Collectors;
@@ -27,7 +30,9 @@
 import org.apache.maven.plugins.annotations.Parameter;
 import org.apache.maven.project.MavenProject;
 import org.eclipse.pde.api.tools.internal.APIFileGenerator;
+import org.eclipse.tycho.BuildPropertiesParser;
 import org.eclipse.tycho.core.TychoProjectManager;
+import org.eclipse.tycho.core.osgitools.DefaultReactorProject;
 import org.eclipse.tycho.model.project.EclipseProject;
 
 /**
@@ -84,9 +89,20 @@ public class ApiFileGenerationMojo extends AbstractMojo {
 	@Parameter(defaultValue = "false", property = "tycho.apitools.generate.skip")
 	private boolean skip;
 
+	/**
+	 * If set to
+	 * <code>true</true> all configured source folders in <code>build.properties</code>
+	 * will be added as {@link #extraSourceLocations}
+	 */
+	@Parameter(defaultValue = "false")
+	private boolean addSourceFolders;
+
 	@Component
 	private TychoProjectManager projectManager;
 
+	@Component
+	private BuildPropertiesParser buildPropertiesParser;
+
 	@Override
 	public void execute() throws MojoExecutionException, MojoFailureException {
 		Optional<EclipseProject> eclipseProject = projectManager.getEclipseProject(project);
@@ -110,13 +126,32 @@ public void execute() throws MojoExecutionException, MojoFailureException {
 				generator.encoding = encoding;
 				generator.debug = debug;
 				generator.manifests = join(extraManifests);
-				generator.sourceLocations = join(extraSourceLocations);
+				if (addSourceFolders) {
+					List<File> list = new ArrayList<>(extraSourceLocations);
+					for (Map.Entry<String, List<String>> entry : buildPropertiesParser
+							.parse(DefaultReactorProject.adapt(project)).getJarToSourceFolderMap().entrySet()) {
+						for (String sourceFolder : entry.getValue()) {
+							list.add(canonicalFile(new File(project.getBasedir(), sourceFolder)));
+						}
+					}
+					generator.sourceLocations = join(list);
+				} else {
+					generator.sourceLocations = join(extraSourceLocations);
+				}
 				generator.generateAPIFile();
 			}
 		}
 	}
 
-	private String join(List<File> list) {
+	private static File canonicalFile(File file) {
+		try {
+			return file.getCanonicalFile();
+		} catch (IOException e) {
+		}
+		return file;
+	}
+
+	private static String join(List<File> list) {
 		return list.isEmpty() ? null // join the elements so that the APIFileGenerator splits it correspondingly
 				: list.stream().map(File::toString).collect(Collectors.joining(File.pathSeparator));
 	}