At present, a discovery call looks like this:

Discovery.discover(ServiceType st, FilterSpec fs)

We can use the ServiceType to constrain the ServiceURLs returned by the discovery call to having a specific type (Remoting service type) and scheme. We can use the FilterSpec to constrain the attributes to be present and have specific values. However, these don't easily permit defining constraints on multiple combinations of aspects of a certain ServiceURL without doing possibly multiple discovery calls (e.g. get all service URLs which have scheme = http-remoting and https-remoting, or all ServiceURLs with URI having host = myHost).

If we could supply a Predicate<ServiceURL> parameter to the discovery call, as in:

Discovery.discover(ServiceType st, FilterSpec fs, Predicate<ServiceURL> p)

which would be used to restrict the set of ServiceURLs returned, these sorts of more advanced discovery calls could be easily implemented.