public static CompressionType valueOf(byte value) {
        switch (value) {
            case ((byte) 0):
                return NONE;
            case ((byte) 5):
                return INCOMPRESSIBLE;
            case ((byte) 6):
                return LZ4;
            case ((byte) 7):
                return ZSTD;
            default:
                throw new IllegalArgumentException("Unknown compression type ordinal " + value);
        }
    }
Returns whether this type represent actually compressed data
vespajlib/src/main/java/com/yahoo/compress/CompressionType.java