code: @GET
      @Path("/getPrincipalClass")
      @RolesAllowed("Tester")
      public String getPrincipalClass(@Context SecurityContext sec) {
          Principal user = sec.getUserPrincipal();
          boolean isJsonWebToken = user instanceof JsonWebToken;
          return "isJsonWebToken:" + isJsonWebToken;
      }
docs: Validate that the SecurityContext#getUserPrincipal is a JsonWebToken
  
  @param sec
  @return