Invalid response in mod_assign_get_submission_status WS

This is the invalid response:

lastattempt => Invalid response value detected: submission => Invalid response value detected: plugins => Invalid response value detected: editorfields => Invalid response value detected: description => Invalid response value detected: Invalid external api response: the value is \"<br \/>\", the server was expecting \"text\" type

This is happening when there are plugins installed that are returning the editor field description including HTML. The param is set to PARAM_TEXT so the WS response fails.

Example of get_editor_fields, as we can see is returning a description using get_string (that means that it may content html):

    public function get_editor_fields() {

        return array('onlinetext' => get_string('pluginname', 'assignsubmission_comments'));

    }