CC-3034: Customized the ES JarHell utility to ignore module-info files

The `module-info` files will appear in multiple JARs, and they are not duplicates. The ES JarHell utility that the Elasticsearch project uses in their tests and base classes for tests (which we inherit and use in our tests) doesn’t take the `module-info` files into account.

A similar fix was made for and backported to all ES 6.x branches (see elastic/elasticsearch#32985), but it was intentionally not backported.

Author: rhauch

src/test/java/org/elasticsearch/bootstrap/JarHell.java

@@ -258,6 +258,14 @@ public static void checkJavaVersion(String resource, String targetVersion) {
   }
 
   static void checkClass(Map<String,Path> clazzes, String clazz, Path jarpath) {
+    if (clazz.equals("module-info") || clazz.endsWith(".module-info")) {
+      // Ignore jigsaw module descriptions
+      return;
+    }
+    if (clazz.startsWith(JarHell.class.getName())) {
+      // Obviously a duplicate of this class
+      return;
+    }
     Path previous = clazzes.put(clazz, jarpath);
     if (previous != null) {
       if (previous.equals(jarpath)) {