Enable code generation for OpenFeign with Spring-Boot 2 (#9118)

[unmerge]

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• Ran the shell script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh and ./bin/security/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates). Windows batch files can be found in .\bin\windows\.
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  @davidkiss

Description of the PR

#9118 [JAVA] Enable code generation for OpenFeign with Spring-Boot 2

When using generation library spring-cloud, code will be generated with import:

import org.springframework.cloud.netflix.feign.FeignClient;

But when one wants to use open feign with spring boot 2, we need the following:

import org.springframework.cloud.openfeign.FeignClient;

Solution: Setup property to switch between both import statements (JavaSpring library spring-cloud) -> apiClient.mustache.

[HugoMario]

thanks a lot @unmerge

[chrisplyn]

@HugoMario Hi Hugo, I am still having trouble generating feign client with spring 2, can you describe a little bit how to use this feature?

[HugoMario]

hey @chrisplyn, sorry for delay. Can you please share more details about the errors you got?