Mirror are now included in the returned list of known locations

p2-maven-plugin/src/main/java/org/eclipse/tycho/p2maven/repository/DefaultRepositoryIdManager.java

@@ -40,6 +40,11 @@ public class DefaultRepositoryIdManager implements IRepositoryIdManager {
 
     private Map<URI, String> knownMavenRepositoryIds = new ConcurrentHashMap<>();
 
+	/**
+	 * Map of known mirror identifiers, indexed by their URI.
+	 */
+	private Map<URI, String> knownMavenMirrorIds = new ConcurrentHashMap<>();
+
     @Override
     public void addMapping(String mavenRepositoryId, URI location) {
         if (mavenRepositoryId == null)
@@ -52,6 +57,15 @@ public void addMapping(String mavenRepositoryId, URI location) {
             logger.warn("p2 repository with URL " + key + " is associated with multiple IDs; was '" + previousValue
                     + "', now is '" + mavenRepositoryId + "'");
         }
+
+		// Checks if a mirror exists for the given location
+		MavenRepositoryLocation repositoryLocation = new MavenRepositoryLocation(mavenRepositoryId, key);
+		MavenRepositoryLocation mirrorLocation = settings.getMirror(repositoryLocation);
+		if (mirrorLocation != null) {
+			// A mirror exists. Adds its id to the map of known mirror ids.
+			URI mirrorKey = normalize(mirrorLocation.getURL());
+			knownMavenMirrorIds.put(mirrorKey, mirrorLocation.getId());
+		}
     }
 
     private static URI normalize(URI location) {
@@ -118,8 +132,8 @@ private static boolean certainlyNoRemoteURL(URI location) {
 
     @Override
 	public Stream<MavenRepositoryLocation> getKnownMavenRepositoryLocations() {
-        return knownMavenRepositoryIds.entrySet().stream()
-                .map(e -> new MavenRepositoryLocation(e.getValue(), e.getKey()));
+		return Stream.concat(knownMavenRepositoryIds.entrySet().stream(), knownMavenMirrorIds.entrySet().stream())
+				.map(e -> new MavenRepositoryLocation(e.getValue(), e.getKey()));
     }
 
 	@Override