Or slightly less efficient as it uses reflection and does not give you the option to use POF, you could use the Coherence IsNullFilter
employeeCache.entrySet( new EqualsFilter(AddressExtractor,null) );
The above code assumes you have a getAddress method on your Employee. An IsNullFilter is actually a subclass of EqualsFilter anyway so all it really does is saves you a bit of typing.
employeeCache.entrySet( new IsNullFilter("getAddress") );