Experimental support for filterChecks trait

The gerrit-code-review-plugin v0.4.0 introduces the
integration with Gerrit Checks plugin. Introduce the option
to query for pending checks.

Change-Id: Idb3f290121aa6fbcdc25a0821c9bdc3dd03e21af

jenkins_jobs/modules/project_multibranch.py

@@ -569,6 +569,13 @@ def gerrit_scm(xml_parent, data):
         (like to disable SCM triggering or to override the pipeline durability)
         (optional)
         Refer to :func:`~property_strategies <property_strategies>`.
+    :arg dict filter-checks: Enable the filtering by pending checks, allowing to
+        discover the changes that need validation only. This feature is using
+        the gerrit checks plugin.
+        (optional)
+        query-operator: Name of the query operator, supported values are:
+            'SCHEME' or 'ID'.
+        query-string: Value of the query operator.
 
     Minimal Example:
 
@@ -635,6 +642,20 @@ def gerrit_scm(xml_parent, data):
     if data.get("build-strategies", None):
         build_strategies(xml_parent, data)
 
+    # FilterChecks Trait
+    checks = data.get("filter-checks", None)
+    if checks:
+        checks_trait = XML.SubElement(
+            traits, "jenkins.plugins.gerrit.traits.FilterChecksTrait"
+        )
+        checks_source_mapping = [
+            ("query-operator", "queryOperator", None),
+            ("query-string", "queryString", None),
+        ]
+        helpers.convert_mapping_to_xml(
+            checks_trait, checks, checks_source_mapping, fail_required=True
+        )
+
 
 def git_scm(xml_parent, data):
     r"""Configure Git SCM

tests/multibranch/fixtures/scm_gerrit_full.xml

@@ -47,6 +47,10 @@
                 </jenkins.plugins.git.traits.RefSpecsSCMSourceTrait_-RefSpecTemplate>
               </templates>
             </jenkins.plugins.git.traits.RefSpecsSCMSourceTrait>
+            <jenkins.plugins.gerrit.traits.FilterChecksTrait>
+              <queryOperator>SCHEME</queryOperator>
+              <queryString>jenkins</queryString>
+            </jenkins.plugins.gerrit.traits.FilterChecksTrait>
           </traits>
         </source>
         <strategy class="jenkins.branch.DefaultBranchPropertyStrategy">

tests/multibranch/fixtures/scm_gerrit_full.yaml

@@ -11,6 +11,9 @@ scm:
             all-branches:
                 - suppress-scm-triggering: true
                 - pipeline-branch-durability-override: max-survivability
+        filter-checks:
+            query-operator: 'SCHEME'
+            query-string: 'jenkins'
         build-strategies:
             - tags:
                 ignore-tags-newer-than: 1