public void put(Attrs attrs, T value) {
            Objects.requireNonNull(attrs, "attrs");
            Objects.requireNonNull(value);
            attrs.storage.put(this, value);
        }
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