Allow to set additional Http headers directly on the IClientExecutable

[ohr]

I'd like to propose an extension to the IClientExecutable interface that allows to set arbitrary HTTP headers. This is an alternative to using AdditionalRequestHeadersInterceptor, with one important difference: it makes the client stateless so it can even be reused with header values like OAuth2 tokens that change with every request.
And I think it's simply more straightforward to use.

[jamesagnew]

Is there a reason you wouldn't just use AdditionalRequestHeadersInterceptor to add arbitrary headers?

[ohr]

It's too static - the interceptor has predefined header/value pairs. interceptRequest(IHttpRequest theRequest) allows no further client-side context (like information of the user for whom the request is executed).
This forces me to either create a new IRestfulClient for every request or to use Thread-Local variables; and both is not nice for the simple task of adding a header.
Also, the majority of IClientInterceptor implementations deal with adding HTTP headers (all suffer from the same restrictions I mentioned above), so a more straightforward API seems justified for me.