@Override
    public SliceRange sliceRange() {
        if (sealed) {
            return SliceRange.of(startOffsetInStream, startOffsetInStream + endOffset);
        } else {
            return SliceRange.of(startOffsetInStream, Offsets.NOOP_OFFSET);
        }
    }
the real start offset of this segment in the stream.
core/src/main/scala/kafka/log/streamaspect/DefaultElasticStreamSlice.java