Some README says hostnames should be updated into the policy file as there is no hostname placeholder in that file (5 occurrences) :
./Security/jmxmp/subject_delegation/README:# paths & hostnames as needed.
./Security/jmxmp/fine_grained/README:# paths & hostnames as needed.
./Security/rmi/subject_delegation/README:# paths & hostnames as needed.
./Security/rmi/fine_grained/README:# paths & hostnames as needed.
./Lookup/jini/README:# Replace file paths and hostnames and port number where needed

It the customer chooses to use other urls that might contain a hostname, it is his choice, out of the README's scope.