private ConfigClass addConfigClass(ConfigClass configClass) {
   if (configClass != null) {
     configClass.setConfigClassRegistry(this);
     configClassesByName.put(configClass.getFullName(), configClass);
   }
   return configClass;
 }
 private void addSourceConfigClass(
     Map<String, File> sourceFilesByName, File sourceFile, ConfigClass configClass) {
   if (configClass != null) {
     String qname = configClass.getFullName();
     File existingConfigClassSourceFile = sourceFilesByName.get(qname);
     if (existingConfigClassSourceFile != null) {
       throw new ExmlcException(
           String.format(
               "Config class '%s' already declared in file %s.",
               qname, existingConfigClassSourceFile.getPath()),
           sourceFile,
           null);
     } else {
       sourceFilesByName.put(qname, sourceFile);
       sourceConfigClasses.add(configClass);
     }
   }
 }