protected boolean isKeyAttribute(AttributeRole attributeRole) throws OperatorException {
  return false;
}

protected boolean isKeyAttribute ( AttributeRole attributeRole ) throws OperatorException { return false ; }
the method iskeyattribute can be overwritten by subclasses which are using key attributes , in order to determine if a specific attribute is used as a join key . by default , there is no use of key attributes , so the method returns false .
