In previous post I asked about question based in part on the premiss that Google did not recommend using Spring in AppEngine. I stand corrected. They now have a page explaining how to optimize the use of Spring.
Google has changed their position on this. I’ve been involved in writing courses for Google on GCP, I’m certified on GCP, and I’m an authorized trainer. In the past there were documentation pages and teaching material warning about the “boot time” of an AppEngine instance. This time must be very short to support the scaling. Google warned about using 3rd party frameworks that would slow boot time. They included Spring in a list of examples of frameworks to avoid.
They have clearly changed their position (and I’m glad!) this is the new page describing Spring —>
https://cloud.google.com/appengine/articles/spring_optimization
I’m sorry for any confusion my post may have caused!