PaperMC/paper-server/nms-patches/net/minecraft/server/commands/PlaceCommand.patch

--- a/net/minecraft/server/commands/PlaceCommand.java
+++ b/net/minecraft/server/commands/PlaceCommand.java
@@ -132,6 +132,7 @@
         if (!structurestart.isValid()) {
             throw PlaceCommand.ERROR_STRUCTURE_FAILED.create();
         } else {
+            structurestart.generationEventCause = org.bukkit.event.world.AsyncStructureGenerateEvent.Cause.COMMAND; // CraftBukkit - set AsyncStructureGenerateEvent.Cause.COMMAND as generation cause
             StructureBoundingBox structureboundingbox = structurestart.getBoundingBox();
             ChunkCoordIntPair chunkcoordintpair = new ChunkCoordIntPair(SectionPosition.blockToSectionCoord(structureboundingbox.minX()), SectionPosition.blockToSectionCoord(structureboundingbox.minZ()));
             ChunkCoordIntPair chunkcoordintpair1 = new ChunkCoordIntPair(SectionPosition.blockToSectionCoord(structureboundingbox.maxX()), SectionPosition.blockToSectionCoord(structureboundingbox.maxZ()));