Sorry for bad eng.
Code of this blockpopulator: https://github.com/Dinnerbone/BukkitFullOfMoon/blob/master/src/main/java/com/dinnerbone/bukkit/moon/MoonCraterPopulator.java
.Server stops responding after this last message in console: "Preparing spawn area: 100%" without any crash log.
On 1.12 works perfectly, without any problem. (1.13 not tested). i'm also pass false to setType() in order to avoid physics updates. And nothing has changed, server anyway freezes