code: public void setNull(long mask) {
  		for (int i = 0; i < this.numFields; i++, mask >>>= 1) {
  			if ((mask & 0x1) != 0) {
  				internallySetField(i, null);
  			}
  		}
  	}
docs: Sets the fields to <code>null</code> using the given bit mask.
  The bits correspond to the individual columns: <code>(1 == nullify, 0 == keep)</code>.
  
  @param mask Bit mask, where the i-th least significant bit represents the i-th field in the record.