public <S extends Packet> boolean isMatch( @Nonnull S stanza )
        {
            if (!hasFMUCElement(stanza)) {
                throw new IllegalArgumentException( "Provided stanza must be a stanza that was sent by remote FMUC node, but was not (the FMUC child element is missing): " + stanza );
            }

            if (!stanza.getClass().equals(type)) {
                return false;
            }

            if (!stanza.getFrom().asBareJID().equals( remoteFMUCNode )) {
                return false;
            }

            // All child elements of the echo'd stanza must equal the original.
            return elements.equals( stanza.getElement().elements() );
        }
Represents a callback waiting for a stanza to be echo'd back from a remote FMUC node.
xmppserver/src/main/java/org/jivesoftware/openfire/muc/spi/FMUCHandler.java