gistfile1.java

// Current definitions 

public interface Service extends Serializable {
}

public interface ServiceRegistry extends Serializable {
    public <R extends Service> R getService(Class<R> serviceRole);
    public <R extends Service> void registerService(Class<R> serviceRole, R service);
    public <R extends Service> void registerServiceInitiator(ServiceInitiator<R> initiator);
}

gistfile2.java

// Considering

public interface Service<T> extends Serializable {
}

public interface ServiceRegistry<T> extends Serializable {
    public <R extends Service<T>> R getService(Class<R> serviceRole);
    public <R extends Service<T>> void registerService(Class<R> serviceRole, R service);
    public <R extends Service<T>> void registerServiceInitiator(ServiceInitiator<R> initiator);
}