code: public static NewGTFSError forLine (Table table, int lineNumber, NewGTFSErrorType errorType, String badValue) {
          NewGTFSError error = new NewGTFSError(table.getEntityClass(), errorType);
          error.lineNumber = lineNumber;
          error.badValue = badValue;
          return error;
      }
docs: Factory Builder for cases where an entity has not yet been constructed, but we know the line number.