static FilterImpl create(final String path, String acceptType, final Filter filter) {
        if (acceptType == null) {
            acceptType = DEFAULT_ACCEPT_TYPE;
        }
        return new FilterImpl(path, acceptType, filter) {
            @Override
            public void handle(Request request, Response response) throws Exception {
                filter.handle(request, response);
            }
        };
    }
Wraps the filter in FilterImpl

@param path       the path
@param acceptType the accept type
@param filter     the filter
@return the wrapped route
src/main/java/spark/FilterImpl.java