HTTPCLIENT-2321 Clarify default implementation of HttpClientConnectio…

[kwin]

…nManager

Add table with default implementations for all relevant component.

[ok2c]

@kwin In all honesty next time I am going to touch HttpClientBuilder I am not sure I will get around to updating this table. It will ultimately rot and will cause more harm than good.

In any case If you want this change-set committed, please at the very least update HttpAsyncClientBuilder, CachingHttpClientBuilder and CachingHttpAsyncClientBuilder

[kwin]

I know this is a lot of effort. The other alternative would be to establish a common naming (e.g. always use Default prefix, but this won't be backwards compatible) or at least clarify in the javadoc of the implementation whether it is the default one or not. WDYT?

[ok2c]

@kwin As I mentioned in the JIRA I am not in favor of documenting the defaults in javadocs because some people might see them as a part of public contract but you do it consistently across the code base I will review and commit the PR.

[kwin]

You already have that all over the place:

1. httpcomponents-client/httpclient5/src/main/java/org/apache/hc/client5/http/impl/auth/BasicAuthCache.java

   Line 49 in f2b9a37

   * Default implementation of {@link AuthCache}. This implements

2. httpcomponents-client/httpclient5/src/main/java/org/apache/hc/client5/http/cookie/BasicCookieStore.java

   Line 45 in f2b9a37

   * Default implementation of {@link CookieStore}

3. httpcomponents-client/httpclient5/src/main/java/org/apache/hc/client5/http/impl/auth/BasicCredentialsProvider.java

   Line 40 in f2b9a37

   * Default implementation of {@link CredentialsStore}.

4. httpcomponents-client/httpclient5/src/main/java/org/apache/hc/client5/http/impl/DefaultRedirectStrategy.java

   Line 50 in f2b9a37

   * Default implementation of {@link RedirectStrategy}.

5. httpcomponents-client/httpclient5/src/main/java/org/apache/hc/client5/http/impl/DefaultConnectionKeepAliveStrategy.java

   Line 45 in f2b9a37

   * Default implementation of a strategy deciding duration

   
   ....

And yes, you are right, I consider this default part of the contract (i.e. changing it is possible but only in a minor version explicitly stating the change somewhere)

[ok2c]

@kwin Those are the default impl of an interface. They have nothing to do with the behavior of client builders.

[kwin]

Except for the last they are all implementations of an interface which can be set on the HttpClientBuilder. Therefore I assume that the default applies here also.

[ok2c]

@kwin I will have to close this PR unless the proposed changes can be made consistently across the entire code base.