[JENKINS-73775] Replace call to removed CommitBuilder.setEncoding(Str…

…ing) (#2578)

* [JENKINS-73775] Replace call to removed CommitBuilder.setEncoding(String)

JGit 7.0.0 removed the setEncoding(String) method that had been
deprecated previously.  The replacement is setEncoding(Charset).  The JGit
documentation recommends commit.setEncoding(StandardCharsets.UTF_8)

Failure was hidden by the previous setLastModified() exception because
this call happens later in the same calling sequence.

* Exclude org.eclipse.jgit from transitive inclusion

The org.eclipse.jgit jar file is already provided by the git client
plugin.  Let's not risk that a 6.9.0 copy of the library is loaded into
the same Java process that is running either JGit 6.10.0 (with git client
plugin 5.0.0) or JGit 7.0.0 with git client plugin 6.0.0)

blueocean-git-pipeline/pom.xml

@@ -39,6 +39,13 @@
       <artifactId>org.eclipse.jgit.ssh.jsch</artifactId>
       <!-- TODO this is hard to manage; if needed, should be in BOM -->
       <version>6.9.0.202403050737-r</version>
+      <exclusions>
+        <!-- Exclude the jgit library because it is provided by git client plugin -->
+        <exclusion>
+          <groupId>org.eclipse.jgit</groupId>
+          <artifactId>org.eclipse.jgit</artifactId>
+        </exclusion>
+      </exclusions>
     </dependency>
 
     <!-- test dependencies -->

blueocean-git-pipeline/src/main/java/io/jenkins/blueocean/blueocean_git_pipeline/GitUtils.java

@@ -344,7 +344,7 @@ public static void commit(final Repository repo, final String refName, final Str
             final CommitBuilder commit = new CommitBuilder();
             commit.setAuthor(author);
             commit.setCommitter(author);
-            commit.setEncoding(Constants.CHARACTER_ENCODING);
+            commit.setEncoding(StandardCharsets.UTF_8);
             commit.setMessage(message);
             //headId can be null if the repository has no commit yet
             if (headId != null) {