code: public void appendInt(int x) {
          elems = ArrayUtils.ensureCapacity(elems, length + 3);
          elems[length  ] = (byte)((x >> 24) & 0xFF);
          elems[length+1] = (byte)((x >> 16) & 0xFF);
          elems[length+2] = (byte)((x >>  8) & 0xFF);
          elems[length+3] = (byte)((x      ) & 0xFF);
          length = length + 4;
      }
docs: Append an integer as a four byte number.