Correctly look up metadata from checkstyle marker

Rule metadata is registered only under the short name of the rule. But
markers created for checkstyle violations use the fully qualified name
of the checker class instead. Register the fully qualified name as
alternative name in the metadata, and the lookup from a stored marker
works as expected.

Fixes #397

net.sf.eclipsecs.core/src/net/sf/eclipsecs/core/config/meta/MetadataFactory.java

@@ -187,12 +187,21 @@ private static RuleMetadata createRuleMetadata(ModuleDetails moduleDetails) {
             packageTokens[packageTokens.length - 1], MetadataFactory.getDefaultSeverity(),
             false, true, true, false, group);
     ruleMeta.setDescription(moduleDetails.getDescription());
+
+    var altName = moduleDetails.getFullQualifiedName();
+    registerAlternative(altName, ruleMeta);
+
     moduleDetails.getProperties().forEach(modulePropertyDetails -> ruleMeta.getPropertyMetadata()
             .add(createPropertyConfig(moduleDetails, modulePropertyDetails)));
 
     return ruleMeta;
   }
 
+  private static void registerAlternative(String alternativeName, RuleMetadata ruleMetadata) {
+    ruleMetadata.addAlternativeName(alternativeName);
+    sAlternativeNamesMap.put(alternativeName, ruleMetadata);
+  }
+
   /**
    * Create module property config data based on current/default data,
    * which are overridden partially with all the metadata fetched from checkstyle.
@@ -573,12 +582,9 @@ private static void doInitialization() throws CheckstylePluginException {
    * @return
    */
   private static String groupId(String metadataFile) {
-    var start = metadataFile.indexOf("checks/") + 7;
-    var end = metadataFile.lastIndexOf("/");
-    if (start >= end) {
-      return "";
-    }
-    return metadataFile.substring(start, end);
+    String res = StringUtils.substringBetween(metadataFile, "/checks/", "/");
+    res = StringUtils.defaultString(res, metadataFile);
+    return res;
   }
 
   /**
@@ -767,10 +773,7 @@ private static void processModules(Element groupElement, RuleGroupMetadata group
       for (Element altNameEl : moduleEl.elements(XMLTags.ALTERNATIVE_NAME_TAG)) {
 
         String alternativeName = altNameEl.attributeValue(XMLTags.INTERNAL_NAME_TAG);
-
-        // register alternative name
-        sAlternativeNamesMap.put(alternativeName, module);
-        module.addAlternativeName(alternativeName);
+        registerAlternative(alternativeName, module);
       }
 
       // process message keys