cxf-nmr trasport should copy the message header which value is String as the Protocol Header

It's common practices to store the headers which we want to send through the transport as the Protocol headers for further processing.

Here is the mail thread[1] which discusses about it.

[1]http://camel.465427.n5.nabble.com/Headers-get-lost-Jetty-NMR-CXF-tp5722158p5722257.html