code: public static final long toLong(byte[] b) {
          long x = 0;
          for (int i = b.length; i > 0; x |= (b[--i] & 0xffL) << (i << 3));
          return x;
      }
docs: @param b an array of 8 bytes. This value cannot be a null.
  
  @return a unique long value representing the first 8 bytes of the byte array.