code: @Nullable
      public Class<?> findClass(final String className)
      {
          Objects.requireNonNull(className);
  
          try {
              return (Class<?>) findClass.invoke(loader, className);
          } catch (IllegalAccessException | InvocationTargetException e) {
              throw new ParserTransformException("unable to find class by name ("
                  + className + ')', e);
          }
      }
docs: Returns the class with the given name if it has already been loaded by
  the given class loader
  
  <p>If the class has not been loaded yet, this method returns {@code
  null}.</p>
  
  @param className the full name of the class to be loaded
  @return the class instance, if found