private void populateProperties() {
            if (parent == null) return;

            properties.putAll(parent.propertyMap());
        }
Instantiate a request builder with defaults from an existing request.

@param request parent JDisc request
@see HttpRequest#createTestRequest(String, com.yahoo.jdisc.http.HttpRequest.Method)
container-core/src/main/java/com/yahoo/container/jdisc/HttpRequest.java