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)