private @NotNull ByteBuffer computeDataOffsetIfNeededAndReadInputBuffer(ByteBuffer mappedBuffer) {
    int dataOffset = this.dataOffset;
    if (dataOffset == -1) {
      dataOffset = computeDataOffset(mappedBuffer);
    }

    ByteBuffer inputBuffer = mappedBuffer.asReadOnlyBuffer();
    inputBuffer.position(dataOffset);
    inputBuffer.limit(dataOffset + compressedSize);
    return inputBuffer;
  }
private @NotNull ByteBuffer computeDataOffsetIfNeededAndReadInputBuffer(ByteBuffer mappedBuffer)