title: Pre-Defined parameters no longer passed to child job
body: <p>I upgraded Jenkins today from 1.618 to 2.3.  This included installing a whole bunch of plugins that it recommended (Mostly Pipeline plugins and their dependencies).</p>
  
  <p>Since the upgrade, I get a new error (or, at least, a new unwanted behavior) any time a job kicks off another job.  Any values passed to the child as "Predefined parameters" are ignored unless the child job already has those keys defined.</p>
  
  <p>Let me illustrate:  Let's say that I have a <code>parent</code> job and a <code>child</code> job.</p>
  
  <p><code>Parent</code> launches <code>child</code> through a "Trigger parameterized build on other projects" Post-build Action.  In the definition of that Post-build Action, under the "Predefined parameters", I have <code>FOO=BAR</code> defined.</p>
  
  <p>In Jenkins 1.618, when <code>child</code> was triggered this way, it would have <code>FOO</code> set as a parameter, with a value of <code>BAR</code>.</p>
  
  <p>But in 2.3, <code>FOO</code> is not set on that build of <code>child</code>.</p>
  
  <p>If I modify <code>child</code> so that <code>FOO</code> is always a parameter of that job, it will then pick up the <code>FOO=BAR</code> set from <code>parent</code>.  This is an unacceptable work-around because we pass dozens of parameters this way, and defining them on both ends is too fragile and violates the "don't repeat yourself" principle.</p>
  
  <p>I get the same results whether I'm triggering the child job through through the "Trigger parameterized build on other projects" Post-build Action or through a MultiJob Phase of a MultiJob project.</p>
  
  <p>Is this an intended change?  Was it broken before, and we were just using it incorrectly?  Or is this a bug?</p>