for(Map.Entry<Address, Rsp<T>> entry: requests.entrySet()) {
Address member=entry.getKey();
if(!(member instanceof SiteAddress))
continue;
SiteAddress addr=(SiteAddress)member;
if(addr.getSite().equals(site)) {
Rsp<T> rsp=entry.getValue();
if(rsp != null) {
if(rsp.setUnreachable()) {
changed=true;
lock.lock();