I’m pretty sure you would have to change some code. I’ve never used Multiverse, so I can’t help you much. But, this is what I think.
You could do what @Kars said or you could just use java 8 to compile the plugin. That’s what I use. I had the problem in the beginning, but once I...
Did you try installing the file for a 1.8 server?
In your essentials config, set change-playerlist to true.
Separate names with a comma.