@staticmethod<EOL><INDENT>def import_activity_to_graph(diagram_graph, process_id, process_attributes, element):<DEDENT>
BpmnDiagramGraphImport.import_flow_node_to_graph(diagram_graph, process_id, process_attributes, element)<EOL>element_id = element.getAttribute(consts.Consts.id)<EOL>diagram_graph.node[element_id][consts.Consts.default] = element.getAttribute(consts.Consts.default)if element.hasAttribute(consts.Consts.default) else None<EOL>
Method that adds the new element that represents BPMN activity.
Should not be used directly, only as a part of method, that imports an element which extends Activity element
(task, subprocess etc.)

:param diagram_graph: NetworkX graph representing a BPMN process diagram,
:param process_id: string object, representing an ID of process element,
:param process_attributes: dictionary that holds attribute values of 'process' element, which is parent of
   imported flow node,
:param element: object representing a BPMN XML element which extends 'activity'.