kie-issues#776: automate PR merge into protected branches

.ci/jenkins/Jenkinsfile.post-release

@@ -78,7 +78,7 @@ pipeline {
                         }
 
                         // Tag repository
-                        githubscm.tagLocalAndRemoteRepository('origin', getKogitoVersion(), getGitAuthorCredsId(), env.BUILD_TAG, true)
+                        githubscm.tagLocalAndRemoteRepository('origin', getKogitoVersion(), getGitAuthorPushCredsId(), env.BUILD_TAG, true)
                     }
                 }
             }

.ci/jenkins/Jenkinsfile.setup-branch

@@ -32,7 +32,8 @@ pipeline {
     }
 
     environment {
-        CI_EMAIL_TO = credentials("${JENKINS_EMAIL_CREDS_ID}")
+        CI_EMAIL_TO = credentials("${JENKINS_EMAIL_CREDS_ID}")\
+        PR_BRANCH_HASH = "${util.generateHash(10)}"
     }
 
     stages {
@@ -107,16 +108,19 @@ pipeline {
                             if (!antoraConfig.content.sources[0].branches.find { it == getBuildBranch() }) {
                                 antoraConfig.content.sources[0].branches.add(getBuildBranch())
                         }
-                    }
 
                         // Add changed files, commit, open and merge PR
                         if (githubscm.isThereAnyChanges()) {
+                            String branchName = getPRBranchName()
+                            githubScm.createBranch(branchName)
                             githubscm.setUserConfigFromCreds(getGitAuthorPushCredsId())
                             githubscm.commitChanges("Add branch ${getBuildBranch()} for generation")
-                            githubscm.pushObject('origin', 'main', getGitAuthorPushCredsId())
+                            String prLink = commitAndCreatePR("Add branch ${getBuildBranch()} for generation", branchName,"main")
+                            approveAndMergePR(prLink)
                         } else {
                             echo 'No changes to push.'
                         }
+                    }
                 }
             }
         }
@@ -171,3 +175,22 @@ void updateYaml(String filePath, Closure updateClosure) {
 boolean isMainBranch() {
     return env.IS_MAIN_BRANCH ? env.IS_MAIN_BRANCH.toBoolean() : false
 }
+
+void approveAndMergePR(String prLink) {
+    if (prLink?.trim()) {
+        githubscm.approvePR(prLink, getGitAuthorPushCredsId())
+        githubscm.mergePR(prLink, getGitAuthorPushCredsId())
+    }
+}
+
+String commitAndCreatePR(String commitMsg, String localBranch, String targetBranch) {
+    def prBody = "Generated by build ${BUILD_TAG}: ${BUILD_URL}"
+    githubscm.setUserConfigFromCreds(getGitAuthorPushCredsId())
+    githubscm.commitChanges(commitMsg)
+    githubscm.pushObject('origin', localBranch, getGitAuthorPushCredsId())
+    return githubscm.createPR(commitMsg, prBody, targetBranch, getGitAuthorCredsId())
+}
+
+String getPRBranchName() {
+    return "${getKogitoVersion().toLowerCase()}-${env.PR_BRANCH_HASH}"
+}