    @Test
    public void testMetadata() {

        JoinGroupRequestData.JoinGroupRequestProtocolCollection serialized = coordinator.metadata();
        assertEquals(1, serialized.size());

        JoinGroupRequestData.JoinGroupRequestProtocol defaultMetadata = serialized.iterator().next();
        assertEquals(KarelDbCoordinator.KDB_SUBPROTOCOL_V0, defaultMetadata.name());
        KarelDbIdentity state
            = KarelDbProtocol.deserializeMetadata(ByteBuffer.wrap(defaultMetadata.metadata()));
        assertEquals(LEADER_INFO, state);
    }