code: public List<Peer> findPeersOfAtLeastVersion(long protocolVersion) {
          lock.lock();
          try {
              ArrayList<Peer> results = new ArrayList<>(peers.size());
              for (Peer peer : peers)
                  if (peer.getPeerVersionMessage().clientVersion >= protocolVersion)
                      results.add(peer);
              return results;
          } finally {
              lock.unlock();
          }
      }
docs: Returns an array list of peers that implement the given protocol version or better.