@Override
    synchronized int numBuffered() {
        return wrapped.numBuffered();
    }
@Test
    public void testNumBufferedWithTopicPartition() {
        final TopicPartition partition = new TopicPartition("topic", 0);
        final int numBuffered = 1;
        when(wrapped.numBuffered(partition)).thenReturn(numBuffered);

        final int result = synchronizedPartitionGroup.numBuffered(partition);

        assertEquals(numBuffered, result);
        verify(wrapped, times(1)).numBuffered(partition);
    }