[DS] [lifecycle methods returning service properties] How should this work?

[David Jencks]

cf FELIX-3506, 3377.

Right now we have it set up so that a lifecycle method can return the exact set 
of service properties it wants the service registration to have.  I'm not at 
all sure this is a plausible way to operate since usually you'd use this 
feature to set or unset a flag in the service properties based on some aspect 
of the component state.  I could be missing something, but I don't see an easy 
way to get the existing set of service properties so you can modify them with 
your flag.  I did something like this:

        serviceProperties.clear();
        for (String key : cc.getServiceReference().getPropertyKeys()) {
            serviceProperties.put(key, 
cc.getServiceReference().getProperty(key));
        }
//now actually add/remove my flag


I think it would be a lot more usable to have the lifecycle methods return a 
map of changes, where a null value for a key means "remove the key".

Have I missed an easy way to use the current implementation?

thanks
david jencks