code: public LZ4Compressor highCompressor(int compressionLevel) {
      if(compressionLevel > MAX_COMPRESSION_LEVEL) {
        compressionLevel = MAX_COMPRESSION_LEVEL;
      } else if (compressionLevel < 1) {
        compressionLevel = DEFAULT_COMPRESSION_LEVEL;
      }
      return highCompressors[compressionLevel];
    }
docs: Returns a {@link LZ4Compressor} which requires more memory than
  {@link #fastCompressor()} and is slower but compresses more efficiently.
  The compression level can be customized.
  <p>For current implementations, the following is true about compression level:<ol>
  <li>It should be in range [1, 17]</li>
  <li>A compression level higher than 17 would be treated as 17.</li>
  <li>A compression level lower than 1 would be treated as 9.</li>
  </ol>
  
  @param compressionLevel the compression level between [1, 17]; the higher the level, the higher the compression ratio
  @return a {@link LZ4Compressor} which requires more memory than
  {@link #fastCompressor()} and is slower but compresses more efficiently.