def __init__(self, source_ref, target_ref):
        """
        Default constructor, initializes object fields with new instances.
        Fields (except inherited):
        - name: name of element. Must be either None (name is optional according to BPMN 2.0 XML Schema) or String.
        - source_ref: an ID of source node. Required field. Must be a String type.
        - target_ref: an ID of target node. Required field. Must be a String type.
        - message_ref: an ID of referenced message element. Must be either None (message_ref is optional according to
        BPMN 2.0 XML Schema) or String.
        """
        if source_ref is None or not isinstance(source_ref, str):
            raise TypeError("SourceRef is required and must be set to a String")
        if target_ref is None or not isinstance(source_ref, str):
            raise TypeError("TargetRef is required and must be set to a String")

        super(MessageFlow, self).__init__()
        self.__name = None
        self.__source_ref = source_ref
        self.__target_ref = target_ref
        self.__message_ref = None
def __init__ ( self , source_ref , target_ref ) : if source_ref is None or not isinstance ( source_ref , str ) : raise TypeError ( "SourceRef is required and must be set to a String" ) if target_ref is None or not isinstance ( source_ref , str ) : raise TypeError ( "TargetRef is required and must be set to a String" ) super ( MessageFlow , self ) . __init__ ( ) self . __name = None self . __source_ref = source_ref self . __target_ref = target_ref self . __message_ref = None
Default constructor, initializes object fields with new instances.
        Fields (except inherited):
        - name: name of element. Must be either None (name is optional according to BPMN 2.0 XML Schema) or String.
        - source_ref: an ID of source node. Required field. Must be a String type.
        - target_ref: an ID of target node. Required field. Must be a String type.
        - message_ref: an ID of referenced message element. Must be either None (message_ref is optional according to
        BPMN 2.0 XML Schema) or String.