JavaDoc and performance

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

hawkbit-repository/hawkbit-repository-api/src/main/java/org/eclipse/hawkbit/repository/model/DistributionSet.java

@@ -26,10 +26,25 @@ import org.eclipse.hawkbit.repository.DistributionSetManagement;
 public interface DistributionSet extends NamedVersionedEntity {
 
     /**
-     * @return {@link Set} of assigned {@link DistributionSetTag}s.
+     * @return immutable {@link Set} of assigned {@link DistributionSetTag}s.
      */
     Set<DistributionSetTag> getTags();
 
+    /**
+     * @param tag
+     *            to add
+     * @return <code>true</code> if tag could be added sucessfully (i.e. was not
+     *         already in the list).
+     */
+    boolean addTag(final DistributionSetTag tag);
+
+    /**
+     * @param tag
+     *            to remove
+     * @return <code>true</code> if tag was in the list and removed
+     */
+    boolean removeTag(final DistributionSetTag tag);
+
     /**
      * @return <code>true</code> if the set is deleted and only kept for history
      *         purposes.