public static String toString(byte[] data, int offset, int length) {
        return toString(ByteBuffer.wrap(data, offset, length));
    }
Utility method as toString(byte[]).

@param data
           bytes to decode
@param offset
           index of first byte to decode
@param length
           number of bytes to decode
@return String decoded from UTF-8
vespajlib/src/main/java/com/yahoo/text/Utf8.java