@SuppressWarnings("unchecked")
        public T getOrDefault(Attrs attrs, T defaultValue) {
            Objects.requireNonNull(attrs, "attrs");
            Objects.requireNonNull(defaultValue, "defaultValue");
            T result = (T) attrs.storage.get(this);
            if (result != null) {
                return result;
            }
            return defaultValue;
        }
Returns the value in the attributes or {@code defaultValue} if absent.
@throws NullPointerException if defaultValue is null.
zuul-core/src/main/java/com/netflix/zuul/Attrs.java