@Override
    synchronized long partitionTimestamp(final TopicPartition partition) {
        return wrapped.partitionTimestamp(partition);
    }
@Test
    public void testPartitionTimestamp() {
        final TopicPartition partition = new TopicPartition("topic", 0);
        final long timestamp = 12345678L;
        when(wrapped.partitionTimestamp(partition)).thenReturn(timestamp);

        final long result = synchronizedPartitionGroup.partitionTimestamp(partition);

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