Prepare for Java 25 release Sep 16, 2025 (#496)

The Jenkins project strives to support new Java Long Term Support
releases soon after they are released.  Java 25 is the next LTS release
and is scheduled to release Sep 16, 2025.  The Jenkins project hopes to
compile and test Jenkins core and the top 200 Jenkins plugins with Java
25 before Oct 31, 2025.

Without this change, the plugin does not compile with Java 24.  We expect
Java 25 will be a superset of Java 24, so let's fix compilation with
Java 24 even though Jenkins does not support Java 24.

Also fixes a spotless formatting issue by updating the parent pom.

Supersedes pull requests:

* #492
* #491

Testing done:

* Confirmed that `mvn spotless:apply` does not change formatting with
  either Java 17 or Java 21
* Confirmed that `mvn clean verify` passes on Linux with Java 24

Author: MarkEWaite

pom.xml

@@ -4,7 +4,7 @@
   <parent>
     <groupId>org.jenkins-ci.plugins</groupId>
     <artifactId>plugin</artifactId>
-    <version>5.7</version>
+    <version>5.18</version>
     <relativePath />
   </parent>
   <groupId>io.jenkins.plugins</groupId>

src/main/java/io/jenkins/plugins/gitlabbranchsource/GitLabSCMNavigator.java

@@ -342,8 +342,7 @@ private String getProjectName(GitLabApi gitLabApi, int projectNamingStrategy, Pr
         String fullPath = project.getPathWithNamespace();
         String projectName;
         switch (projectNamingStrategy) {
-            default:
-                // for legacy reasons default naming strategy is set to Full Project path
+            default: // for legacy reasons default naming strategy is set to Full Project path
             case 1:
                 projectName = fullPath;
                 break;