code: @Override
      public void filter(ContainerRequestContext requestContext,
                         ContainerResponseContext responseContext) throws IOException {
          int status = responseContext.getStatus();
          if (status == 404 || status == UnprocessableEntityException.STATUS) {
              String path = mappedViewPath();
              if (path != null) {
                  responseContext.setEntity(Viewables.newDefaultViewable(path),
                          new Annotation[0], MediaType.TEXT_HTML_TYPE);
                  responseContext.setStatus(Response.Status.OK.getStatusCode());
              }
          }
      }
docs: {@inheritDoc}