Finish all todos in keyvault-jca's first PR.

[chenrujun]

#16452

1. Remove usage of httpclient5
   [Done] : Modify the dependency httpclient5 to httpclient4. #20191

2. Pass check of maven-checkstyle-plugin, spotbugs-maven-plugin, revapi-maven-plugin
   Done

3. Support different cloud env
   https://dev.azure.com/azure-spring-integration/spring-integration-private/_sprints/backlog/spring-integration-private%20Team/spring-integration-private/186?workitem=953
   Done: Configure cloud from keyvault uri #20530

4. Certificates downloaded from Key Vault through the get secret API might be in PKCS12 or PEM format. These can be differentiated by the by the contentType of the secret bundle.
   Done. But need more tests. @lzc-1997-abel Please add tests in this issue: Add more tests for azure-security-keyvault-jca #20589

5. move code under certificates starter to jca library
   Calceled.

6. OAUTH2_MANAGED_IDENTITY_TOKEN_URL to apply on all azure platforms(only IMDS??)
   Done.

7. authclient to support new pattern of url
   Done.

[chenrujun]

Hi, @lzc-1997-abel .

Certificates downloaded from Key Vault through the get secret API might be in PKCS12 or PEM format. These can be differentiated by the by the contentType of the secret bundle.

What's current status of this task?

[chenrujun]

Closing this issue because all sub tasks been finished.

And we will add tests in this issue: #20589