code: public String attachments(String mediatype, String id, String documentId) throws ApiException {
          ApiResponse<String> resp = attachmentsWithHttpInfo(mediatype, id, documentId);
          return resp.getData();
      }
docs: Get the attachment of the interaction
  Get the attachment of the interaction specified in the documentId path parameter
  @param mediatype media-type of interaction (required)
  @param id id of interaction (required)
  @param documentId id of document to get (required)
  @return String
  @throws ApiException If fail to call the API, e.g. server error or cannot deserialize the response body