Enables content negotiation through a query parameter, instead of the Accept Header.
To enable this feature, use the context-param in web.xml:
<context-param>
<param-name>resteasy.media.type.param.mapping</param-name>
<param-value>someName</param-value>
</context-param>
So, in a request like
http://service.foo.com/resouce?someName=application/xml
the application/xml media type will received the highest priority in the content negotiation.
In the cases where the request contains both the parameter and the Accept header, the parameter will be more relevant.
It is possible to left the param-value empty, what will cause the processor to look for an accept parameter.
