Merge pull request #747 from jenkinsci/revert-744-app-org-different-from-repo-org

Revert "Do not enforce GitHub app to comes from the same org as the repo org. The GH app can come from another org as log as it is installed in the org with the target git repo there is no security issue"

Author: jtnord

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

@@ -326,6 +326,9 @@ public String getUsername() {
     @NonNull
     public synchronized GitHubAppCredentials withOwner(@NonNull String owner) {
         if (this.owner != null) {
+            if (!owner.equals(this.owner)) {
+                throw new IllegalArgumentException("Owner mismatch: " + this.owner + " vs. " + owner);
+            }
             return this;
         }
         if (byOwner == null) {