Null check plugin input for servers

api/src/main/java/net/md_5/bungee/api/event/ServerConnectEvent.java

@@ -2,6 +2,7 @@ package net.md_5.bungee.api.event;
 
 import lombok.Data;
 import lombok.EqualsAndHashCode;
+import lombok.NonNull;
 import lombok.ToString;
 import net.md_5.bungee.api.config.ServerInfo;
 import net.md_5.bungee.api.connection.ProxiedPlayer;
@@ -21,6 +22,7 @@ public class ServerConnectEvent extends Event implements Cancellable
     /**
      * Server the player will be connected to.
      */
+    @NonNull
     private ServerInfo target;
     /**
      * Cancelled state.

proxy/src/main/java/net/md_5/bungee/UserConnection.java

@@ -171,6 +171,8 @@ public final class UserConnection implements ProxiedPlayer
 
     public void connect(ServerInfo info, final boolean retry)
     {
+        Preconditions.checkNotNull( info, "info" );
+
         ServerConnectEvent event = new ServerConnectEvent( this, info );
         if ( bungee.getPluginManager().callEvent( event ).isCancelled() )
         {