public static void main(String[] args)
{
    Set<Server> servers = getServers();
    Map<String, String> serverData = new ConcurrentHashMap<>();

    for (Server server : servers)
    {
        String serverId = server.getIdentifier();
        String data = server.fetchData();

        serverData.put(serverId, data);
    }
}

Set<Server> servers = getServers();
    Map<String, String> serverData = new ConcurrentHashMap<>();

    servers.parallelStream().forEach((server) -> {
        serverData.put(server.getIdentifier(), server.fetchData());
    });

servers.parallelStream().forEach(server -> {
    serverData.put(server.getIdentifier(), server.fetchData());
});

final Set<Server> servers = getServers();
Map<String, String> serverData = servers.parallelStream().collect(
    toConcurrentMap(Server::getIdentifier, Server::fetchData));

import java.io.Console;
import java.util.ArrayList;

ArrayList<String> list = new ArrayList<>();
list.add("Item1");
list.add("Item2");
list.parallelStream().forEach((o) -> {
    System.out.print(o);
});

public staic void main(String[] args)
{
    Set<Server> servers = getServers();
    Map<String, String> serverData = new ConcurrentHashMap<>();

    Parallel.ForEach(servers, new LoopBody<Server>()
    {
        public void run(Server server)
        {
             String serverId = server.getIdentifier();
             String data = server.fetchData();

             serverData.put(serverId, data);
        }
    });
}