NameFetcher.java

package me.projectx.Settlements.Utils;

import com.google.common.collect.ImmutableList;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;

import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.Callable;

public class NameFetcher implements Callable<Map<UUID, String>> {
    private static final String PROFILE_URL = "https://sessionserver.mojang.com/session/minecraft/profile/";
    private final JSONParser jsonParser = new JSONParser();
    private final List<UUID> uuids;
    public NameFetcher(List<UUID> uuids) {
        this.uuids = ImmutableList.copyOf(uuids);
    }

    @Override
    public Map<UUID, String> call() throws Exception {
        Map<UUID, String> uuidStringMap = new HashMap<UUID, String>();
        for (UUID uuid: uuids) {
            HttpURLConnection connection = (HttpURLConnection) new URL(PROFILE_URL+uuid.toString().replace("-", "")).openConnection();
            JSONObject response = (JSONObject) jsonParser.parse(new InputStreamReader(connection.getInputStream()));
            String name = (String) response.get("name");
            if (name == null) {
                continue;
            }
            String cause = (String) response.get("cause");
            String errorMessage = (String) response.get("errorMessage");
            if (cause != null && cause.length() > 0) {
                throw new IllegalStateException(errorMessage);
            }
            uuidStringMap.put(uuid, name);
        }
        return uuidStringMap;
    }
}

PlayerCommand.java

package me.projectx.Settlements.Commands;

import java.sql.SQLException;

import me.projectx.Settlements.Managers.ChunkManager;
import me.projectx.Settlements.Managers.PlayerManager;
import me.projectx.Settlements.Managers.SettlementManager;
import me.projectx.Settlements.Models.CommandModel;
import me.projectx.Settlements.Models.Settlement;
import me.projectx.Settlements.Utils.ClaimType;
import me.projectx.Settlements.Utils.CommandType;
import me.projectx.Settlements.Utils.MessageType;
import me.projectx.Settlements.Utils.PlayerUtils;

import org.bukkit.command.CommandSender;
import org.bukkit.entity.Player;

public class CommandSettlementPlayer extends CommandModel {

	public CommandSettlementPlayer() {
		super("settlement.player", "/s");
	}

	@Override
	public boolean onCmd(CommandSender sender, String cml, String[] args) throws SQLException {
		if (cml.equalsIgnoreCase("s")){
			if (args.length > 0){				
				switch(args[0]){ //removed all the unnecessary stuff
					case "id":
						Player p = (Player)sender;
						p.sendMessage(PlayerUtils.getNameFromUUID(p.getUniqueId())); //returns null
						break;
					default:
						sender.sendMessage(MessageType.COMMAND_INVALID_ARGUMENT.getMsg() + " Type /s for help");
						break;
				}
			}
		}
		return true;
	}
}

PlayerUtils.java

package me.projectx.Settlements.Utils;

import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.UUID;

import me.projectx.Settlements.Main;

import org.bukkit.entity.Player;
import org.bukkit.scheduler.BukkitRunnable;

public class PlayerUtils {
	
	private static Map<UUID, String> response = new HashMap<UUID, String>();
	
	public static String getNameFromUUID(final UUID id){
		new BukkitRunnable(){
			public void run(){
				NameFetcher nf = new NameFetcher(Arrays.asList(id));
				try {
					response = nf.call();
				} catch(Exception e) {
					e.printStackTrace();
				}		
			}
		}.runTaskAsynchronously(Main.getInstance());
		return response.get(id);
	}
}