Spring Refactor some test code to use lambda expressions and method references

Hi,

I refactored some test codes to use lambda expression and method reference for the sake of conciseness.

Due to an issue of java language itself described in #22509, tests that includes addConverter was refactored with input/output type informations.

I checked that build done successfully using ./gradlew check

Thanks.

Comment From: sbrannen

This has been merged into 5.3.x and main.

Thanks, and congratulations on submitting your first PR to the Spring Framework!