Some plugins do not record their results in every build: code coverage, for example, can be disabled on a
per-build basis. If the automatically selected reference build does not contain such a report, then no delta
report can be computed at all - the delta results are then silently empty.

<p>
  With this parameter you can restrict the search for a reference build to those builds that provide a specific
  action (i.e., a specific report). All builds that do not provide such an action will be skipped, and the search
  continues with the predecessors of these builds.
</p>

<p>
  The action can be specified either by its fully qualified class name or by its simple class name. Supertypes and
  interfaces of the actual action are considered as well, so it is possible to filter for a whole family of
  actions. Some examples:
</p>
<dl>
  <dt>io.jenkins.plugins.coverage.metrics.steps.CoverageBuildAction</dt>
  <dd>The reference build must contain a code coverage report of the coverage plugin</dd>
  <dt>CoverageBuildAction</dt>
  <dd>The same filter, using the simple class name</dd>
  <dt>&lt;empty&gt;</dt>
  <dd>The type of the action is not relevant (this is the default behavior if unset)</dd>
</dl>