Suppress addition of unnecessary repo-refereces when assembling p2-repos

RELEASE_NOTES.md

@@ -28,8 +28,11 @@ Repositories can contain references to other repositories (e.g. to find addition
 ```
 ### new option to filter added repository-references when assembling a p2-repository
 
-The repository references automatically added to a assembled p2-repository (via `tycho-p2-repository-plugin`'s `addIUTargetRepositoryReferences` or `addPomRepositoryReferences`) 
-can now be filtered by their location using exclusion and inclusion patterns and therefore allows more fine-grained control which references are added.
+If filtering provided artifacts is enabled, the repository references automatically added to a assembled p2-repository
+(via `tycho-p2-repository-plugin`'s `addIUTargetRepositoryReferences` or `addPomRepositoryReferences`) can now be filtered by their location
+using exclusion and inclusion patterns and therefore allows more fine-grained control which references are added.
+Additionally the automatically added references can be filter based on if they provide any of the filtered units or not.
+If `addOnlyProviding` is `true` repositories that don't provide any filtered unit are not added to the assembled repo.
 ```xml
 <plugin>
 	<groupId>org.eclipse.tycho</groupId>
@@ -38,6 +41,7 @@ can now be filtered by their location using exclusion and inclusion patterns and
 	<configuration>
 		... other configuration options ...
 		<repositoryReferenceFilter>
+			<addOnlyProviding>true</addOnlyProviding>
 			<exclude>
 				<location>https://foo.bar.org/hidden/**</location>
 				<location> %regex[http(s)?:\/\/foo\.bar\.org\/secret\/.*]</location>

tycho-core/src/main/java/org/eclipse/tycho/p2/tools/DestinationRepositoryDescriptor.java

@@ -28,10 +28,12 @@ public class DestinationRepositoryDescriptor {
     private final boolean append;
     private final Map<String, String> extraArtifactRepositoryProperties;
     private final List<RepositoryReference> repositoryReferences;
+    private final List<RepositoryReference> filterablRepositoryReferences;
 
     public DestinationRepositoryDescriptor(File location, String name, boolean compress, boolean xzCompress,
             boolean keepNonXzIndexFiles, boolean metaDataOnly, boolean append,
-            Map<String, String> extraArtifactRepositoryProperties, List<RepositoryReference> repositoryReferences) {
+            Map<String, String> extraArtifactRepositoryProperties, List<RepositoryReference> repositoryReferences,
+            List<RepositoryReference> filterablRepositoryReferences) {
         this.location = location;
         this.name = name;
         this.compress = compress;
@@ -41,12 +43,13 @@ public DestinationRepositoryDescriptor(File location, String name, boolean compr
         this.append = append;
         this.extraArtifactRepositoryProperties = extraArtifactRepositoryProperties;
         this.repositoryReferences = repositoryReferences;
+        this.filterablRepositoryReferences = filterablRepositoryReferences;
     }
 
     public DestinationRepositoryDescriptor(File location, String name, boolean compress, boolean xzCompress,
             boolean keepNonXzIndexFiles, boolean metaDataOnly, boolean append) {
         this(location, name, compress, xzCompress, keepNonXzIndexFiles, metaDataOnly, append, Collections.emptyMap(),
-                Collections.emptyList());
+                Collections.emptyList(), Collections.emptyList());
     }
 
     public DestinationRepositoryDescriptor(File location, String name) {
@@ -88,4 +91,8 @@ public Map<String, String> getExtraArtifactRepositoryProperties() {
     public List<RepositoryReference> getRepositoryReferences() {
         return repositoryReferences == null ? Collections.emptyList() : repositoryReferences;
     }
+
+    public List<RepositoryReference> getFilterableRepositoryReferences() {
+        return filterablRepositoryReferences;
+    }
 }

tycho-core/src/main/java/org/eclipse/tycho/p2/tools/mirroring/facade/MirrorApplicationService.java

@@ -54,7 +54,11 @@ public interface MirrorApplicationService {
      *            Whether to include bundles mentioned in the require section of a feature
      * @param includeRequiredFeatures
      *            Whether to include features mentioned in the require section of a feature
-     * @param filterProvided Whether to filter IU/artifacts that are already provided by a referenced repository
+     * @param filterProvided
+     *            Whether to filter IU/artifacts that are already provided by a referenced
+     *            repository
+     * @param addOnlyProvidingRepoReferences
+     *            Whether to add only repository-references that provide any relevant IU
      * @param filterProperties
      *            additional filter properties to be set in the p2 slicing options. May be
      *            <code>null</code>
@@ -64,7 +68,8 @@ public interface MirrorApplicationService {
     public void mirrorReactor(RepositoryReferences sources, DestinationRepositoryDescriptor destination,
             Collection<DependencySeed> seeds, BuildContext context, boolean includeAllDependencies,
             boolean includeAllSource, boolean includeRequiredBundles, boolean includeRequiredFeatures,
-            boolean filterProvided, Map<String, String> filterProperties) throws FacadeException;
+            boolean filterProvided, boolean addOnlyProvidingRepoReferences, Map<String, String> filterProperties)
+            throws FacadeException;
 
     /**
      * recreates the metadata of an existing repository e.g. to account for changes in the contained

tycho-core/src/main/java/org/eclipse/tycho/p2tools/MirrorApplicationServiceImpl.java

@@ -152,7 +152,8 @@ private static IQuery<IInstallableUnit> createQuery(IUDescription iu) {
     public void mirrorReactor(RepositoryReferences sources, DestinationRepositoryDescriptor destination,
             Collection<DependencySeed> projectSeeds, BuildContext context, boolean includeAllDependencies,
             boolean includeAllSource, boolean includeRequiredBundles, boolean includeRequiredFeatures,
-            boolean filterProvided, Map<String, String> filterProperties) throws FacadeException {
+            boolean filterProvided, boolean addOnlyProvidingRepoReferences, Map<String, String> filterProperties)
+            throws FacadeException {
         final TychoMirrorApplication mirrorApp = createMirrorApplication(sources, destination, agent);
 
         // mirror scope: seed units...
@@ -162,6 +163,7 @@ public void mirrorReactor(RepositoryReferences sources, DestinationRepositoryDes
         mirrorApp.setIncludeRequiredBundles(includeRequiredBundles);
         mirrorApp.setIncludeRequiredFeatures(includeRequiredFeatures);
         mirrorApp.setFilterProvided(filterProvided);
+        mirrorApp.setAddOnlyProvidingRepoReferences(addOnlyProvidingRepoReferences);
         mirrorApp.setEnvironments(context.getEnvironments());
         SlicingOptions options = new SlicingOptions();
         options.considerStrictDependencyOnly(!includeAllDependencies);