code: public void setFormFields(List<FormField> formFields) throws HelloSignException {
          clearList(DOCUMENT_FORM_FIELDS);
          for (FormField formField : formFields) {
              addFormField(formField);
          }
      }
docs: Overwrites the form fields for this document. This is useful when
  manually migrating form fields from a template.
  
  @param formFields List
  @throws HelloSignException thrown if there is a problem adding the
  FormFields to this Document.