public Map<TopicPartition, Long> beginningOffsets(Collection<TopicPartition> partitions, Timer timer) {
        return beginningOrEndOffset(partitions, ListOffsetsRequest.EARLIEST_TIMESTAMP, timer);
    }
@Test
    public void testBeginningOffsetsEmpty() {
        buildFetcher();
        assertEquals(emptyMap(), offsetFetcher.beginningOffsets(emptyList(), time.timer(5000L)));
    }