Issue #7789 : Accept underscores in host names when building the request origin

[vbhanuchander-lang]

Addresses #7789 — with one correction to the scope, which I've also raised on the issue.

The proxy leg was already fine

Both transforms pass the proxy to HttpClientManager.HttpClientBuilderFacade#setProxy, which builds
it with new HttpHost(scheme, host, port) and sets it on RequestConfig. That constructor takes the
host name verbatim, so my_proxy.internal survives it. Verified against httpcore5 5.4.

The request target was not

Http#processRow and HttpPost#processRow call HttpHost.create(uri), and that overload reads
URI.getHost(). When a host name contains an underscore, java.net.URI classifies the authority as
registry-based rather than server-based, and the parsed components are simply not available:

http://my_service.internal:8080/api
   URI.getHost()      = null
   URI.getPort()      = -1
   URI.getUserInfo()  = null
   URI.getAuthority() = my_service.internal:8080

HttpHost.create(URI) then fails with NullPointerException: Host name. The same call appears in
WebService and in HttpProtocol, so four call sites share the defect.

Change

HttpClientManager.createHttpHost(URI) uses getHost() when it is available and otherwise parses
the authority — dropping userinfo, taking the port when one is present, and leaving IPv6 literals
intact. All four call sites now go through it.

Underscores are not legal in host names per RFC 1123, which the reporter rightly notes. But they are
common in internal and container DNS and they resolve, so failing with a NullPointerException
rather than either working or reporting a clear error seems the wrong outcome either way.

Tests

Seven tests in a new HttpClientManagerTest:

• a normal server-based authority
• an underscored host with a port, and without one
• userinfo dropped from the origin
• an IPv6 literal kept intact
• a URI with no host at all, and a non-numeric port — both rejected with IllegalArgumentException
  rather than an NPE

Five of the seven fail with NullPointerException: Host name if createHttpHost is changed to
delegate back to HttpHost.create(uri).

Verification

• mvn -pl core,plugins/transforms/http,plugins/transforms/httppost,plugins/transforms/webservices -Pskip-uitest test
  — core 1138, http 37, httppost 25, webservices 6, all passing, 0 failures
• mvn spotless:check and mvn apache-rat:check pass on the five touched modules

If it turns out the reporter really did hit the proxy path rather than the target, then this is still
a genuine fix for the four call sites above but the issue would need to stay open — I've asked them
to confirm.

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• I hereby declare this contribution to be licensed under the Apache License Version 2.0, January 2004