So I have managed to get the Sponge server in an odd state. Upon typing /stop, it says Stopping server… in chat, but does not actually stop the server. This happened both from console and from chat. I can’t reproduce it and I can’t explain it. The fact that I was running it in debug mode off of IntelliJ through SpongeStart probably has something to do with it. I did think to create a heap dump; it can be found here. Thoughts?
I often use /stop both from console and ingame and I never had this bug. It might be environnement related.
Like I said, I can’t reproduce it. It was just a random derp, and probably related to the fact that it’s in an IDE’s debug mode. I’m interested to know why it happened though. 
I had a similar situation for another sponge api4. In the console simulation normal operation. Connection of the client. I decided to not force quit. After ~5-7 minutes it is off. Sorry for bad English.
Windows 7
No, it didn’t freeze the server. I could repeatedly type /stop and it would repeatedly say that the server is stopping. Block breaking, etc. worked normally.
Hmm… I have no idea what I was trying to say… something like the console is freezing? Anyway, what your describing did happen to me, just disregard my earlier comment 
It seemed like the server would stop eventually, or that typing /stop a lot would shut it down, but I couldn’t really figure it out.
Edit: and it did not happen in my IDE
I’ve had this happen couple times before as well. Performed hard reset. Couldn’t reproduce it after.