code: public static void addRowMapping(Class returnTypeClass, Class<? extends RowMapper> rowMapperClass) {
          _rowMappings.put(returnTypeClass, rowMapperClass);
      }
docs: Add a new row mapper to the list of available row mappers.  The getRowMapper method traverses the
  list of mappers from beginning to end, checking to see if a mapper can handle the specified
  returnTypeClass.  There is a default mapper which is used if a match cannot be found in the list.
  
  @param returnTypeClass Class which this mapper maps a row to.
  @param rowMapperClass  The row mapper class.