code: public static Set<Field> getDeclaredFields(Class<?> clazz, FieldFilter filter) {
          Set<Field> fields = new HashSet<Field>();
          Field[] allFields = clazz.getDeclaredFields();
          for(Field field : allFields) {
              if(filter.passFilter(field)) {
                  fields.add(field);
              }
          }
          return fields;
      }
docs: Returns a set of all fields matching the supplied filter
  declared in the clazz class.
  
  @param clazz     The class to inspect.
  @param filter    Filter to use.
  
  @return All matching fields declared by the clazz class.