public byte [] decompress(ByteBuffer input, int uncompressedLen) {
        ByteBuffer uncompressed = ByteBuffer.allocate(uncompressedLen);
        compressor.decompressUnconditionally(input, uncompressed);
        return uncompressed.array();
    }
Wrapper for LZ4 compression that selects compression level based on properties.

@author Ulf Lilleengen
config/src/main/java/com/yahoo/vespa/config/LZ4PayloadCompressor.java