WorkflowDefinition
    graph       WorkflowGraph
    scope       WorkflowInstanceScope'

WorkflowInstance
    definition  WorkflowDefinition
    graph       WorkflowGraph
    scope       WorkflowInstanceScope

WorkflowWorkflow
    instance    WorkflowInstance
    graph       WorkflowGraph
    initiator   UserId Maybe
    payload     WorkflowPayload
    currentNode WorkflowGraphNodeLabel Maybe