default FilterSyncType getSyncType() {
        Filter f = getClass().getAnnotation(Filter.class);
        if (f != null) {
            return f.sync();
        }
        throw new UnsupportedOperationException("not implemented");
    }
Called by zuul filter after request is processed by this filter.
zuul-core/src/main/java/com/netflix/zuul/filters/ZuulFilter.java