The basic usage case is to block a Transition of a Parent Issue until all its Sub-Tasks are Resolved or Closed.
But it may be also these others use cases:
Block a Resolve transition until Linked Issues having a Block Issue Link Type are Resolved.
Or Block Start Progress Transition of a Sub-Task until its Parent Issue is In Progress
and many others ....
How it works
By defining this Workflow Condition in a Transition of your workflow, you are able to block/allow the transition depending of the Status reached by Linked Issues .
By Linked Issues, the condition considers all Issue Link Type (included Sub-Task) in both direction (Inward and Outwards Link).
Configuring the Feature
To configure the Block Linked Issues depending on Status Workflow Condition, please follow these steps :
Add the Block Linked Issues depending on Status to the wanted transition.