configureAndRefreshWebApplicationContext change to requireNonNullElseGet if use jdk 17

Comment From: jhoeller

Generally speaking, this new Objects.requireNonNullElseGet method is indeed useful for such scenarios. However, in our framework codebase, I'd rather leave such simple if checks in place with dedicated if/else code blocks, allowing for inline documentation of each block and making the structure easy to grasp visually. Also, a regular if construct is slightly more efficient than a lambda-provided supplier at runtime.

Thanks for the PR, in any case!