code: public static void setUser(String user) {
      if (user != null && user.length() > 0) {
        RaygunClient.user = user;
      }
    }
docs: Sets the current user of your application. If user is an email address which is associated with a Gravatar,
  their picture will be displayed in the error view. If this is not called a random ID will be assigned.
  If the user context changes in your application (i.e log in/out), be sure to call this again with the
  updated user name/email address.
  @param user A user name or email address representing the current user