We've bean using URLConnectionHTTPConduit since very start of CXF for so many years, and it's stable.

The new introduced in-jdk api based HttpClientHTTPConduit still has potential issues(even from JDK api itself with some JDK versions). For example this one which is reported upstream recently

https://issues.apache.org/jira/browse/CXF-8987

We better use URLConnectionHTTPConduit as the default one and document this.

In CXF we have a system property as a switch "org.apache.cxf.transport.http.forceURLConnection" which can determine to use URLConnectionHTTPConduit or HttpClientHTTPConduit. I think in our product we better use URLConnectionHTTPConduit as the default one(to make the value of "org.apache.cxf.transport.http.forceURLConnection" as true)