A step descriptor that returns true from takesImplicitBlockArgument now requires a body.
The API states:
Return true if this step can accept an implicit block argument. (If it can, but it is called without a block, StepContext.hasBody() will be false.)
Steps should not require bodies that are implicit/optionally indicated.
This was introduced in this PR
(Marked as Blocker because it has explicitly broken a stated API)