Common superclass for workflow (approval) work item, certification work item and case management work item.

Item Summary
Name	Type	Multiplicity	Description
name	property PolyStringType	[0,1]	Descriptive name of the work item.
stageNumber	property int	[0,1]	Number of the stage this work item is part of.
createTimestamp	property dateTime	[0,1]	When was this work item created?
deadline	property dateTime	[0,1]	When is this work to be done? May be moved via escalation(s).
originalAssigneeRef	reference ObjectReferenceType	[0,1]	Original assignee for this work item.
assigneeRef	reference ObjectReferenceType	[0,-1]	Users to which the work item is assigned.
candidateRef	reference ObjectReferenceType	[0,-1]	Users and abstract roles to which the work item MAY BE assigned.
performerRef	reference ObjectReferenceType	[0,1]	User who actually executed (completed) this work item.
escalationLevel	property WorkItemEscalationLevelType	[0,1]	TODO
output	container AbstractWorkItemOutputType	[0,1]	Work item output (if any).
closeTimestamp	property dateTime	[0,1]	When was this work item closed.

Items
- name
  
  Flags: RAM,runtime
  
  Multiplicity: [0,1]
  
  Descriptive name of the work item. E.g. "Assign role1 to user1".
- stageNumber
  
  Flags: RAM,runtime
  
  Multiplicity: [0,1]
  
  Number of the stage this work item is part of.
- createTimestamp
  
  Flags: RAM,runtime
  
  Multiplicity: [0,1]
  
  When was this work item created?
- deadline
  
  Flags: RAM,runtime
  
  Multiplicity: [0,1]
  
  When is this work to be done? May be moved via escalation(s).
- originalAssigneeRef
  
  Flags: RAM
  
  Multiplicity: [0,1]
  
  Original assignee for this work item.
- assigneeRef
  
  Flags: RAM
  
  Multiplicity: [0,-1]
  
  Users to which the work item is assigned. Other users do not see such a work item in their work lists. Normally the work item is assigned to a single user. However, when delegating (directly or via escalation) more assignees could be added.
- candidateRef
  
  Flags: RAM
  
  Multiplicity: [0,-1]
  
  Users and abstract roles to which the work item MAY BE assigned.
- performerRef
  
  Flags: RAM
  
  Multiplicity: [0,1]
  
  User who actually executed (completed) this work item.
- escalationLevel
  
  Flags: RAM,runtime
  
  Multiplicity: [0,1]
  
  TODO
- output
  
  Flags: RAM,runtime
  
  Multiplicity: [0,1]
  
  Work item output (if any).
- closeTimestamp
  
  Flags: RAM,runtime
  
  Multiplicity: [0,1]
  
  When was this work item closed. (If null, it is considered open.)