HttpComponentsMessageSender has two constructors, with and without HttpClient, and the one with HttpClient omits adding a SoapRemoveHeaderInterceptor.
This breaks in org.apache.http.protocol.RequestContent with
new ProtocolException("Content-Length header already present"),
but only in some containers (oc4j) and not in others (jetty, eclipe); this makes the issue hard to debug.
Adding a note to the javadoc would help the developer pick the proper constructor to avoid this issue.
git pull request coming up.