code: public void pointTo(Object baseObject, long baseOffset, int sizeInBytes) {
      assert numFields >= 0 : "numFields (" + numFields + ") should >= 0";
      assert sizeInBytes % 8 == 0 : "sizeInBytes (" + sizeInBytes + ") should be a multiple of 8";
      this.baseObject = baseObject;
      this.baseOffset = baseOffset;
      this.sizeInBytes = sizeInBytes;
    }
docs: Update this UnsafeRow to point to different backing data.
  
  @param baseObject the base object
  @param baseOffset the offset within the base object
  @param sizeInBytes the size of this row's backing data, in bytes