Acceptance Criteria (Required on creation):

Either of the following options

• the form keys are not initialized per se for Task Queries in the REST API
• the potential performance impact of this behavior is well-documented

Hints (Optional):

The flag initializeFormKeys is enabled for Task Queries in the

• REST API for Task Queries
• Filter Queries in general
• it might make sense to only keep it activated for fetching single tasks in the REST API
   

Original Description:

When a task or list of tasks is queried  (such as the Camunda /tasks endpoint or the Camunda Tasklist app), if a task has a Form Key which is a expression, the expression is evaluated for every task that is returned in the list.

There needs to be a big documentation notification about this implication: Users can use variables to store a dynamic form key.  But the implications are not clear: Every single task has a initialization of the form key.

In the Camunda Tasklist app, there is auto refresh that occurs of you leave task list open... and so if enough users have this open, there is a exponential performance impact.

Very likely this should be seen as a bug/performance impact feature that should move form key initialization as an optional item in the API response, and the Camunda Tasklist only initializes the form key when the user selects the task.

You can observe the behaviour by placing a breakpoint at:

https://github.com/camunda/camunda-bpm-platform/blob/master/engine/src/main/java/org/camunda/bpm/engine/impl/delegate/ExpressionGetInvocation.java#L40