[JENKINS-60874] Configuring ForkPullRequestDiscoveryTrait using Job DSL (#752)

JENKINS-26535 describes an issue where wildcards in generics aren't
handled well and result in the inability to configure classes that use
wildcards in Job DSL, such as the SCMHeadAuthority class used for the
forked PR trust policy. To work around this issue, create a new abstract
class named GitHubForkTrustPolicy which extends the necessary
SCMHeadAuthority superclass with its proper generics and use it in the
constructor instead. Update all the trust policies to extend from this
abstract class so they can be used.

Fixes JENKINS-60874.

Author: mtughan

src/main/java/org/jenkinsci/plugins/github_branch_source/ForkPullRequestDiscoveryTrait.java

@@ -39,7 +39,6 @@
 import jenkins.scm.api.trait.SCMHeadAuthority;
 import jenkins.scm.api.trait.SCMHeadAuthorityDescriptor;
 import jenkins.scm.api.trait.SCMSourceContext;
-import jenkins.scm.api.trait.SCMSourceRequest;
 import jenkins.scm.api.trait.SCMSourceTrait;
 import jenkins.scm.api.trait.SCMSourceTraitDescriptor;
 import jenkins.scm.impl.ChangeRequestSCMHeadCategory;
@@ -83,6 +82,12 @@ public class ForkPullRequestDiscoveryTrait extends SCMSourceTrait {
      * @param trust the authority to use.
      */
     @DataBoundConstructor
+    public ForkPullRequestDiscoveryTrait(int strategyId, @NonNull GitHubForkTrustPolicy trust) {
+        this.strategyId = strategyId;
+        this.trust = trust;
+    }
+
+    @Deprecated
     public ForkPullRequestDiscoveryTrait(
             int strategyId,
             @NonNull
@@ -236,17 +241,23 @@ public List<SCMHeadAuthorityDescriptor> getTrustDescriptors() {
         }
     }
 
+    /** Trust policy for forked pull requests.
+     * <p>
+     * This reduces generics in the DataBoundConstructor signature as a workaround for JENKINS-26535.
+     */
+    public abstract static class GitHubForkTrustPolicy
+            extends SCMHeadAuthority<GitHubSCMSourceRequest, PullRequestSCMHead, PullRequestSCMRevision> {}
+
     /** An {@link SCMHeadAuthority} that trusts nothing. */
-    public static class TrustNobody
-            extends SCMHeadAuthority<SCMSourceRequest, PullRequestSCMHead, PullRequestSCMRevision> {
+    public static class TrustNobody extends GitHubForkTrustPolicy {
 
         /** Constructor. */
         @DataBoundConstructor
         public TrustNobody() {}
 
         /** {@inheritDoc} */
         @Override
-        public boolean checkTrusted(@NonNull SCMSourceRequest request, @NonNull PullRequestSCMHead head) {
+        public boolean checkTrusted(@NonNull GitHubSCMSourceRequest request, @NonNull PullRequestSCMHead head) {
             return false;
         }
 
@@ -270,8 +281,7 @@ public boolean isApplicableToOrigin(@NonNull Class<? extends SCMHeadOrigin> orig
     }
 
     /** An {@link SCMHeadAuthority} that trusts contributors to the repository. */
-    public static class TrustContributors
-            extends SCMHeadAuthority<GitHubSCMSourceRequest, PullRequestSCMHead, PullRequestSCMRevision> {
+    public static class TrustContributors extends GitHubForkTrustPolicy {
         /** Constructor. */
         @DataBoundConstructor
         public TrustContributors() {}
@@ -303,8 +313,7 @@ public boolean isApplicableToOrigin(@NonNull Class<? extends SCMHeadOrigin> orig
     }
 
     /** An {@link SCMHeadAuthority} that trusts those with write permission to the repository. */
-    public static class TrustPermission
-            extends SCMHeadAuthority<GitHubSCMSourceRequest, PullRequestSCMHead, PullRequestSCMRevision> {
+    public static class TrustPermission extends GitHubForkTrustPolicy {
 
         /** Constructor. */
         @DataBoundConstructor
@@ -347,15 +356,14 @@ public boolean isApplicableToOrigin(@NonNull Class<? extends SCMHeadOrigin> orig
     }
 
     /** An {@link SCMHeadAuthority} that trusts everyone. */
-    public static class TrustEveryone
-            extends SCMHeadAuthority<SCMSourceRequest, PullRequestSCMHead, PullRequestSCMRevision> {
+    public static class TrustEveryone extends GitHubForkTrustPolicy {
         /** Constructor. */
         @DataBoundConstructor
         public TrustEveryone() {}
 
         /** {@inheritDoc} */
         @Override
-        protected boolean checkTrusted(@NonNull SCMSourceRequest request, @NonNull PullRequestSCMHead head) {
+        protected boolean checkTrusted(@NonNull GitHubSCMSourceRequest request, @NonNull PullRequestSCMHead head) {
             return true;
         }
 

src/test/java/org/jenkinsci/plugins/github_branch_source/ForkPullRequestDiscoveryTrait2Test.java

@@ -28,9 +28,6 @@
 import java.util.Collections;
 import java.util.List;
 import jenkins.branch.BranchSource;
-import jenkins.scm.api.SCMRevision;
-import jenkins.scm.api.mixin.ChangeRequestSCMHead2;
-import jenkins.scm.api.trait.SCMHeadAuthority;
 import jenkins.scm.api.trait.SCMSourceTrait;
 import org.jenkinsci.plugins.workflow.multibranch.WorkflowMultiBranchProject;
 import org.junit.Ignore;
@@ -69,8 +66,7 @@ public void configRoundtripWithRawUrl() throws Exception {
 
     private void assertRoundTrip(
             WorkflowMultiBranchProject p,
-            SCMHeadAuthority<? super GitHubSCMSourceRequest, ? extends ChangeRequestSCMHead2, ? extends SCMRevision>
-                    trust,
+            ForkPullRequestDiscoveryTrait.GitHubForkTrustPolicy trust,
             boolean configuredByUrl)
             throws Exception {