code: private TypeElement getSurroundingClass(Element e) throws ProcessingException {
      if (e.getEnclosingElement().getKind() == ElementKind.CLASS) {
        return (TypeElement) e.getEnclosingElement();
      }
  
      throw new ProcessingException(e,
          "Field %s  is not part of a class. Only fields in a class can be annotated with %s",
          e.getSimpleName().toString(), Column.class.getSimpleName());
    }
docs: Checks if a Element is in class and returns the TypeElement of the surrounding class
  
  @param e The element to check
  @return The TypeElement of the surroungin class
  @throws ProcessingException if surround class is not a element