code: public static DiscoverInfo getDiscoverInfoByUser(Jid user) {
          NodeVerHash nvh = JID_TO_NODEVER_CACHE.lookup(user);
          if (nvh == null)
              return null;
  
          return getDiscoveryInfoByNodeVer(nvh.nodeVer);
      }
docs: Get the discover info given a user name. The discover info is returned if
  the user has a node#ver associated with it and the node#ver has a
  discover info associated with it.
  
  @param user
  user name (Full JID)
  @return the discovered info