Remove Apache HttpClient 4 dependency

[clutcher]

As I see org.apache.httpcomponents:httpclient:4.5.3 is needed only for 3 classes - MonitoredConnectionManager, NamedConnectionPool and SSLSocketFactoryAdapter, which are not used anywhere else in the code. Also from what I see in implementation and current state of spring cloud netflix - it looks like eureka-client is now uses everywhere EurekaHttpClient interface and doesn't not need to provide http client implementation itself.

Is it ok if I would raise PR to remove this 3 classes and dependency on httpclient 4? Or I'm missing something and this classes are used somewhere and should be migrated to apache http client 5?

P.S. I'm raising this bug, because time to time I get issue with not working service discovery in Spring Boot/Cloud microservices implementation. Investigation usually shows that including of httpclient4 dependency leads to creating an additional spring bean for http client 4 without full configuration, what leads to not working service discovery clients. To fix this issue is usually enough to explicitly disable dependency on http client 4, as it usually comes with eureka-client dependency, while all other dependency and app implementation already uses http client 5.

[clutcher]

I made a closer look into usage of this classes and httpclient dependency:

• This 3 classes are not really used anywhere in source code and in any of related projects included Spring Cloud ecosystem (checked via search on github and google by full qualified class names).
• httpclient 4 classes are not used anywhere in eureka-client except java doc in EurekaClientConfig
• httpclient 4 classes are used in eureka-client-jersey3 in EurekaJersey3ClientImpl, but implementation are provided by transitive dependency on org.glassfish.jersey.connectors:jersey-apache-connector:3.0.5
• httpclient 4 classes are also used in eureka-core tests in TestableHttpReplicationClient, but implementation are provided by transitive dependency on eureka-test-utils, which depends on eureka-core-jersey3, which depends on org.glassfish.jersey.connectors:jersey-apache-connector:3.0.5

So I will raise a PR to remove that dependency and 3 related classes from eureka-client.

FYI: to disable dependency on httpclient4 in real app I used such build gradle configuraion:

configurations.configureEach {
    exclude(group = "org.apache.httpcomponents", module = "httpclient")
}

[clutcher]

@OlgaMaciaszek @howardyuan @spencergibb May I ask for help with reviewing, merging and releasing this ticket and PR?

[spencergibb]

Olga and I are external contributors and cannot help in merging and releasing this project

[clutcher]

@spencergibb Thanks for response. PR review would also be helpful, while waiting for howardyuan.

[clutcher]

@howardyuan Any chance to move it forward? Maybe I can help somehow with maintaining this repo? Or there is more sense to consider migration on something else as this project looks more like a dead one.