code: public static boolean isFieldExists(Class<?> clas, String fieldName) {
  		Field[] fields = clas.getDeclaredFields();
  		for (Field field : fields) {
  			if (field.getName().equals(fieldName)) {
  				return true;
  			}
  		}
  		if (clas.getSuperclass() != null) {
  			return isFieldExists(clas.getSuperclass(), fieldName);
  		}
  		return false;
  	}
docs: Checks if is field exists.
  
  @param clas      the clas
  @param fieldName the field name
  @return true, if is field exists