[JENKINS-69488] do not SnapShot GitHubAppCredentials

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

@@ -0,0 +1,30 @@
+package org.jenkinsci.plugins.github_branch_source;
+
+import com.cloudbees.plugins.credentials.CredentialsSnapshotTaker;
+import com.cloudbees.plugins.credentials.common.UsernamePasswordCredentials;
+import com.cloudbees.plugins.credentials.impl.UsernamePasswordCredentialsSnapshotTaker;
+import hudson.Extension;
+
+/**
+ * A {@link CredentialsSnapshotTaker} for {@link GitHubAppCredentials} that is a no-op.
+ *
+ * <p>As {@code GitHubAppCredentials} tokens are time limited they need to be refreshed
+ * periodically. This is currently addressed by its use of the {@code writeReplace()} and {@code
+ * readResolve}, but as these credentials are {@link UsernamePasswordCredentials} this behaviour
+ * conflicts with the {@link UsernamePasswordCredentialsSnapshotTaker}. This SnapshotTaker restores
+ * the status quo allowing the Credentials to be replaced using the existing mechanism.
+ */
+@Extension
+public class GitHubAppCredentialsSnapshotTaker
+    extends CredentialsSnapshotTaker<GitHubAppCredentials> {
+
+  @Override
+  public GitHubAppCredentials snapshot(GitHubAppCredentials credentials) {
+    return credentials;
+  }
+
+  @Override
+  public Class<GitHubAppCredentials> type() {
+    return GitHubAppCredentials.class;
+  }
+}