Optional. When specified, only the versions of the resource that made it through the given list of jobs will be considered when triggering and fetching.

Note that if multiple `get`s are configured with `passed` constraints, all of the mentioned jobs are correlated. That is, with the following set of inputs:

    plan:
    - get: a
      passed: [a-unit, integration]
    - get: b
      passed: [b-unit, integration]
    - get: x
      passed: [integration]

This means "give me the versions of `a`, `b`, and `x` that have passed the same build of `integration`, with the same version of `a` passing `a-unit` and the same version of `b` passing `b-unit`."

This is crucial to being able to implement safe "fan-in" semantics as things progress through a pipeline.