code: private ExtensionInfo getExtensionInfo(String className, ClassLoader classLoader) {
          if (extensionInfos == null) {
              extensionInfos = new HashMap<>();
          }
  
          if (!extensionInfos.containsKey(className)) {
              log.trace("Load annotation for '{}' using asm", className);
              ExtensionInfo info = ExtensionInfo.load(className, classLoader);
              if (info == null) {
                  log.warn("No extension annotation was found for '{}'", className);
                  extensionInfos.put(className, null);
              } else {
                  extensionInfos.put(className, info);
              }
          }
  
          return extensionInfos.get(className);
      }
docs: Returns the parameters of an {@link Extension} annotation without loading
  the corresponding class into the class loader.
  
  @param className name of the class, that holds the requested {@link Extension} annotation
  @param classLoader class loader to access the class
  @return the contents of the {@link Extension} annotation or null, if the class does not
  have an {@link Extension} annotation