@Override
    public <V> Map<String, Object> offset(Map<String, V> partition) {
        return offsets(Collections.singletonList(partition)).get(partition);
    }
@Test
    public void should_return_null_offset_for_non_existing_partition() {
        Map<String, String> partition = mapOf("part1", "something");
        State state = new State();
        JetSourceOffsetStorageReader sut = new JetSourceOffsetStorageReader(state);
        Map<String, Object> offset = sut.offset(partition);
        assertThat(offset).isNull();
    }