class PeerGroup extends AbstractExecutionThreadService implements TransactionBroadcaster {

    public void addPeerDiscovery(PeerDiscovery peerDiscovery) {
        lock.lock();
        try {
            if (getMaxConnections() == 0)
                setMaxConnections(DEFAULT_CONNECTIONS);
            peerDiscoverers.add(peerDiscovery);
        } finally {
            lock.unlock();
        }
    }

    public  PeerGroup(NetworkParameters params);
    public  PeerGroup(NetworkParameters params, @Nullable AbstractBlockChain chain);
    public  PeerGroup(NetworkParameters params, @Nullable AbstractBlockChain chain, ClientConnectionManager connectionManager);

}