PaperMC/nms-patches/FluidTypeLava.patch

--- a/net/minecraft/server/FluidTypeLava.java
+++ b/net/minecraft/server/FluidTypeLava.java
@@ -39,6 +39,13 @@
 
                     if (iblockdata.isAir()) {
                         if (this.a((IWorldReader) world, blockposition1)) {
+                            // CraftBukkit start - Prevent lava putting something on fire
+                            if (world.getType(blockposition1).getBlock() != Blocks.FIRE) {
+                                if (org.bukkit.craftbukkit.event.CraftEventFactory.callBlockIgniteEvent(world, blockposition1, blockposition).isCancelled()) {
+                                    continue;
+                                }
+                            }
+                            // CraftBukkit end
                             world.setTypeUpdate(blockposition1, BlockFireAbstract.a((IBlockAccess) world, blockposition1));
                             return;
                         }
@@ -55,6 +62,14 @@
                     }
 
                     if (world.isEmpty(blockposition2.up()) && this.b(world, blockposition2)) {
+                        // CraftBukkit start - Prevent lava putting something on fire
+                        BlockPosition up = blockposition2.up();
+                        if (world.getType(up).getBlock() != Blocks.FIRE) {
+                            if (org.bukkit.craftbukkit.event.CraftEventFactory.callBlockIgniteEvent(world, up, blockposition).isCancelled()) {
+                                continue;
+                            }
+                        }
+                        // CraftBukkit end
                         world.setTypeUpdate(blockposition2.up(), BlockFireAbstract.a((IBlockAccess) world, blockposition2));
                     }
                 }
@@ -144,7 +159,11 @@
 
             if (this.a((Tag) TagsFluid.LAVA) && fluid1.a((Tag) TagsFluid.WATER)) {
                 if (iblockdata.getBlock() instanceof BlockFluids) {
-                    generatoraccess.setTypeAndData(blockposition, Blocks.STONE.getBlockData(), 3);
+                    // CraftBukkit start
+                    if (!org.bukkit.craftbukkit.event.CraftEventFactory.handleBlockFormEvent(generatoraccess.getMinecraftWorld(), blockposition, Blocks.STONE.getBlockData(), 3)) {
+                        return;
+                    }
+                    // CraftBukkit end
                 }
 
                 this.a(generatoraccess, blockposition);