Make the SlackAPI thread-safe in its current implementation

Plugins/Mineplex.Core/src/mineplex/core/slack/SlackAPI.java

@@ -23,13 +23,14 @@ public class SlackAPI
 	public static final String DEFAULT_ICON = ":mineplex:";
 
 	// Singular instance.
-	private static SlackAPI _instance;
+	private static final SlackAPI _instance = new SlackAPI();
 
 	// Don't allow instantiation elsewhere.
 	private SlackAPI() {}
 
 	/**
-	 * Sends a message asynchronously to a Slack channel.
+	 * <p>Sends a message to a Slack channel</p>
+	 * <p>Will be run asynchronously if called from the main thread, else it will execute immediately on the current thread</p>
 	 *
 	 * @param team The team which contains the target channel.
 	 * @param channel The target channel for the message.
@@ -59,7 +60,8 @@ public class SlackAPI
 		if (Bukkit.isPrimaryThread())
 		{
 			ThreadPool.ASYNC.execute(send);
-		} else
+		}
+		else
 		{
 			send.run();
 		}
@@ -132,11 +134,6 @@ public class SlackAPI
 	 */
 	public static SlackAPI getInstance()
 	{
-		if (_instance == null)
-		{
-			_instance = new SlackAPI();
-		}
-
 		return _instance;
 	}
 }