Apache HttpClient socket and connection timeouts overwritten by Feign

[ianfp]

Related to #781 and #517.

As described in #781, Feign overrides the timeouts configured in my Apache RequestConfig, even if I don't set custom request options in the Feign builder. This is unexpected behavior.

The change introduced to fix #517 copies the existing RequestConfig, but then immediately overwrites the timeouts, again, even if no Feign request options are set.

[kdavisk6]

There are always Options set. If you do not specify, the defaults take over. This is one of those areas where I'm unsure how to proceed. One way is to update the documentation to make it clear that not setting Options does not mean there are none and encourage users to set Options, forgoing manipulating the Client directly.

The other is to update each Client to detect when they have been explicitly configured and ignore the incoming Options.

A third potential is to merge the two options together.

However, this leaves us with quite the conundrum, how does Feign know which situation to apply?

What if users want to use Feign's Options and then add additional settings directly on the Client? If we choose to ignore any incoming Options, then the user's expectation is not met. If we merge, we may make the wrong choice and give priority to the wrong group of options. This leads us to the current implementation.

I think the best we can do is update the documentation stating that values in Options will override any Client specific options and that if no Options are set, default Options are used. This way, Feign is not put in the position to attempt to divine what the user wants and leaves it up to the user.

Thoughts?