--- a/java.source/src/org/netbeans/api/java/source/ElementUtilities.java	
+++ a/java.source/src/org/netbeans/api/java/source/ElementUtilities.java	
@@ -70,8 +70,11 @@ 
 import com.sun.tools.javac.util.Context;
 import com.sun.tools.javac.util.Names;
 import com.sun.tools.javadoc.DocEnv;
+import java.io.IOException;
+import java.net.URL;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.EnumSet;
 import java.util.HashMap;
@@ -80,6 +83,8 @@ 
 import java.util.LinkedList;
 import java.util.List;
 import java.util.ListIterator;
+import java.util.Map;
+import java.util.Set;
 import javax.lang.model.element.Element;
 import javax.lang.model.element.ElementKind;
 import javax.lang.model.element.ExecutableElement;
@@ -96,6 +101,10 @@ 
 
 import org.netbeans.modules.java.source.builder.ElementsService;
 import org.netbeans.modules.java.source.JavadocEnv;
+import org.netbeans.modules.java.source.tasklist.TasklistSettings.DependencyTracking;
+import org.netbeans.modules.java.source.util.FindUsagesUtils;
+import org.openide.filesystems.FileObject;
+import org.openide.util.Exceptions;
 
 /**
  *
@@ -536,6 +545,34 @@ 
         return findUnimplementedMethods(impl, impl);
     }
 
+    /**
+     * Finds all subtypes of given types in all known source roots that depend on the current source root.
+     *
+     * @param handles types for which the subtypes should be found
+     * @return all found subtypes for the given types, classified by source root and original type. <code>null</code> may be returned if current the task is canceled.
+     * @since 0.59
+     */
+    public Map<URL, Map<ElementHandle<TypeElement>, Set<ElementHandle<TypeElement>>>> findSubTypes(Collection<? extends ElementHandle<TypeElement>> handles) {
+        FileObject owner = info.getClasspathInfo().getClassPath(ClasspathInfo.PathKind.SOURCE).findOwnerRoot(info.getFileObject());
+
+        if (owner == null) {
+            return Collections.emptyMap();//TODO: log?
+        }
+
+        Map<URL, Map<ElementHandle<TypeElement>, Set<ElementHandle<TypeElement>>>> result = new HashMap<URL, Map<ElementHandle<TypeElement>, Set<ElementHandle<TypeElement>>>>();
+
+        try {
+            if (FindUsagesUtils.findUsages(owner.getURL(), new LinkedList<ElementHandle<TypeElement>>(handles), result, false, true, false, DependencyTracking.ENABLED) == null) {
+                return null;
+            }
+        } catch (IOException ex) {
+            //should not normally happen:
+            Exceptions.printStackTrace(ex);
+        }
+
+        return result;
+    }
+
     // private implementation --------------------------------------------------