FIX: CraftServer.getOfflinePlayers was not converting set->array well.

An incorrect method was being used to convert from Set<OfflinePlayer>
to OfflinePlayer[].

Relates to BUKIT-404

By: Andrew Ardill <andrew.ardill@gmail.com>

paper-server/src/main/java/org/bukkit/craftbukkit/CraftServer.java

@@ -938,6 +938,6 @@ public final class CraftServer implements Server {
         }
         players.addAll(Arrays.asList(getOnlinePlayers()));
 
-        return (OfflinePlayer[]) players.toArray();
+        return players.toArray(new OfflinePlayer[players.size()]);
     }
 }