docs: public void addTemplate( int row,
                               int column,
                               String content ) {
          if ( this.sourceBuilder == null ) {
              throw new DecisionTableParseException(
                      "Unexpected content \"" + content + "\" in cell " +
                              RuleSheetParserUtil.rc2name( row, column ) + ", leave this cell blank" );
          }
          this.sourceBuilder.addTemplate( row, column, content );
      }