chore(dependency): upgrade spring boot from 2.7.x to 3.0.x and spring cloud from 2021.0.x to 2022.0.x

[j-sandy]

Upgrading spring boot 2.7.18 to 3.0.13 and spring cloud 2021.0.8 to 2022.0.5.
Spring cloud release 2022.0.x is compatible with spring boot 3.0.x.
https://github.com/spring-cloud/spring-cloud-release/wiki/Supported-Versions#supported-releases

WebMvcConfigurerAdapter class has been deprecated in Springframework 5.0 and subsequently removed from Springframework 6.0. So, replacing it with WebMvcConfigurer interface for direct implementation.
https://docs.spring.io/spring-framework/docs/5.0.0.RELEASE/javadoc-api/org/springframework/web/servlet/config/annotation/WebMvcConfigurerAdapter.html

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refactor(dependency): replace javax with jakarta and javax.inject with jakarta.inject during upgrade of spring boot 3.0.x

Spring Boot 3.0 has migrated from Java EE to Jakarta EE APIs for all dependencies.
https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-3.0-Release-Notes#third-party-library-upgrades
So, replacing the imports with javax to jakarta.

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refactor(dependency): migrate rxjava to rxjava3 during upgrade of spring boot 3.0.x

Spring boot 3.x deprecated and removed rxjava, and rxjava3 has been added. So, update the dependency.
https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-3.0-Migration-Guide#rxjava

And refactored the code to accomodate changes required by rxjava2 and rxjava3 following the changelogs.
https://github.com/ReactiveX/RxJava/wiki/What's-different-in-2.0
https://github.com/ReactiveX/RxJava/wiki/What%27s-different-in-3.0

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refactor(test): replace spring.profiles with spring.config.activate.on-profile as part of spring boot 3.x upgrade

While upgrading the spring boot to 3.0.13 and spring cloud 2022.0.5, encountered the below error:

Caused by: org.springframework.boot.context.config.InvalidConfigDataPropertyException: Property 'spring.profiles' imported from location 'class path resource [application.yml]' is invalid and should be replaced with 'spring.config.activate.on-profile' [origin: class path resource [application.yml] - 2:13]
	at app//org.springframework.boot.context.config.InvalidConfigDataPropertyException.lambda$throwIfPropertyFound$0(InvalidConfigDataPropertyException.java:113)
	at [email protected]/java.util.LinkedHashMap.forEach(LinkedHashMap.java:721)
	at [email protected]/java.util.Collections$UnmodifiableMap.forEach(Collections.java:1553)

In order to fix this issue, replacing spring.profiles with spring.config.activate.on-profile in application.yml