Index: jackrabbit-core/src/main/java/org/apache/jackrabbit/core/security/user/GroupImpl.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- jackrabbit-core/src/main/java/org/apache/jackrabbit/core/security/user/GroupImpl.java	(revision 1693407)
+++ jackrabbit-core/src/main/java/org/apache/jackrabbit/core/security/user/GroupImpl.java	(revision )
@@ -35,6 +35,7 @@
 import javax.jcr.Property;
 import javax.jcr.PropertyType;
 import javax.jcr.RepositoryException;
+import javax.jcr.UnsupportedRepositoryOperationException;
 import javax.jcr.Value;
 
 import org.apache.jackrabbit.api.security.user.Authorizable;
@@ -172,7 +173,12 @@
         return getMembershipProvider(getNode()).addMember(authImpl);
     }
 
+    @Override
+    public Set<String> addMembers(String... memberIds) throws RepositoryException {
+        throw new UnsupportedRepositoryOperationException("not implemented");
+    }
 
+
     /**
      * @see Group#removeMember(Authorizable)
      */
@@ -186,6 +192,11 @@
         }
 
         return getMembershipProvider(getNode()).removeMember((AuthorizableImpl) authorizable);
+    }
+
+    @Override
+    public Set<String> removeMembers(String... memberIds) throws RepositoryException {
+        throw new UnsupportedRepositoryOperationException("not implemented");
     }
 
     //--------------------------------------------------------------------------
Index: jackrabbit-api/src/main/java/org/apache/jackrabbit/api/security/user/Group.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- jackrabbit-api/src/main/java/org/apache/jackrabbit/api/security/user/Group.java	(revision 1693407)
+++ jackrabbit-api/src/main/java/org/apache/jackrabbit/api/security/user/Group.java	(revision )
@@ -16,8 +16,10 @@
  */
 package org.apache.jackrabbit.api.security.user;
 
+import javax.annotation.Nonnull;
 import javax.jcr.RepositoryException;
 import java.util.Iterator;
+import java.util.Set;
 
 /**
  * A Group is a collection of {@link #getMembers() Authorizable}s.
@@ -69,6 +71,24 @@
     boolean addMember(Authorizable authorizable) throws RepositoryException;
 
     /**
+     * Add one or more member(s) to this Group. Note, that an implementation may
+     * define circumstances under which this method allows to add non-existing
+     * {@code Authorizable}s as new members. Also an implementation may choose to
+     * (partially) postpone validation/verification util {@link Session#save()}.
+     *
+     * @param memberIds The {@code Id}s of the authorizables to be added as
+     * members to this group.
+     * @return a set of those {@code memberIds} that could not be added or an
+     * empty set of all ids have been successfully processed. The former may include
+     * those cases where a given id cannot be resolved to an existing authorizable,
+     * one that is already member or if adding the member would create a
+     * cyclic group membership.
+     * @throws RepositoryException If one of the specified memberIds is invalid or
+     * if some other error occurs.
+     */
+    Set<String> addMembers(@Nonnull String... memberIds) throws RepositoryException;
+
+    /**
      * Remove a member from this Group.
      *
      * @param authorizable The <code>Authorizable</code> to be removed from
@@ -77,4 +97,20 @@
      * @throws RepositoryException If an error occurs.
      */
     boolean removeMember(Authorizable authorizable) throws RepositoryException;
+
+    /**
+     * Remove one or several members from this Group. Note, that an implementation
+     * may define circumstances under which this method allows to remove members
+     * that (no longer) exist. An implementation may choose to (partially)
+     * postpone validation/verification util {@link Session#save()}.
+     *
+     * @param memberIds The {@code Id}s of the authorizables to be removed
+     * from the members of this group.
+     * @return a set of those {@code memberIds} that could not be removed or an
+     * empty set if all ids have been successfully processed. The former may include
+     * those cases where a given id cannot be resolved to an existing authorizable.
+     * @throws RepositoryException If one of the specified memberIds is invalid
+     * or if some other error occurs.
+     */
+    Set<String> removeMembers(@Nonnull String... memberIds) throws RepositoryException;
 }