Reshade httphost

[rnorth]

FYI @dadoonet, relating to #958

As httpcore is a transitive dependency that we don't want to conflict with user's libs, we unfortunately need to:

• roll back Disable shading of Apache HTTP Components/Core libs #959, where we disabled the shading of this module. As is, we're at risk of internal breakage when transitive deps clash.
• in turn, stop exposing HttpHost in our public API. We should take a general stance of keeping our public APIs free of transitive deps (especially shaded ones)

The API method in ElasticsearchContainer will thus change, from:

public HttpHost getHost()

to:

public String getHttpHostAddress()

Usage in turn changes from:

RestClient client = RestClient.builder(container.getHost()).build();

to the slightly more verbose but equivalent:

RestClient client = RestClient.builder(HttpHost.create(container.getHttpHostAddress())).build();

@bsideup, @kiview and I have discussed at length and concluded that this is the only approach that we're comfortable with - despite the fact that this raises an unfortunate breaking change in the API of the Elasticsearch module, which we reluctantly have to do.

We are sorry that we did not catch this particular issue at PR stage - we're going to upgrade our static analysis to guard against inadvertent leakage of shaded dependencies. In the longer term we also, obviously, wish to reduce the weight of our dependency chain, both unshaded and shaded, so that this does not happen again.

We intend for this change to go out as 1.10.1.

I hope this is OK with you @dadoonet - our apologies again for not catching this before release.

[dadoonet]

It looks good to me.