A convenient default RequestHeader => String transformer that removes unique param values in the request uri, instead replacing them with their param names so that all requests to a route get the same Span name.
Provides sugar for creating a new ZipkinHeaderFilter
this will be used to instantiate a ZipkinServiceLike to be used with this filter. It is called a "factory" to emphasise the fact that it will be lazily instantiated so that it is safe depend on a running app.
a method for turning a RequestHeader into a Span name. By default just uses the RequestHeader#path