code: private TypeElement checkAndGetClass(Element e) throws ProcessingException {
  
      if (e.getKind() != ElementKind.CLASS) {
        throw new ProcessingException(e,
            "%s is annotated with @%s but only classes can be annotated with this annotation",
            e.toString(), ObjectMappable.class.getSimpleName());
      }
  
      return (TypeElement) e;
    }
docs: Check the Element if it's a class and returns the corresponding TypeElement
  
  @param e The element to check
  @return The {@link TypeElement} representing the annotated class
  @throws ProcessingException If element is not a CLASS