code: public static Class<? extends RowMapper> replaceRowMapping(Class returnTypeClass, Class<? extends RowMapper> rowMapperClass) {
          return _rowMappings.put(returnTypeClass, rowMapperClass);
      }
docs: Replace a row mapping.
  
  @param returnTypeClass Class which this mapper maps a row to.
  @param rowMapperClass  The row mapper class.
  @return if the mapper was replaced, false mapper for returnTypeClass was not found, no action taken.