As in the title

Don't know about fire but I know there's a method which you can call on the instance of the lightning called something along the lines of "setEffectOnly" which will spawn a lightning that doesn't create fire and doesn't damage entities.

where to look for her?

For a special one that I created
Here is the code

    @Override
    public InteractionResult use(BlockState pState, Level pLevel, BlockPos pPos, Player pPlayer, InteractionHand pHand, BlockHitResult pHit) {
        ItemStack itemStack = pPlayer.getItemInHand(pHand);
        if(itemStack.is(Items.DIAMOND)){
            LightningBolt bolt = new LightningBolt(EntityType.LIGHTNING_BOLT, pLevel);
            bolt.setPos(pPos.getX(), pPos.getY(), pPos.getZ());
            pLevel.addFreshEntity(bolt);
        }else
            pPlayer.sendMessage(new TextComponent("You have no diamond!"), Util.NIL_UUID);

        return InteractionResult.SUCCESS;
    }

 

use LightningBolt#setVisualOnly with parm true, this will stop the LightningBolt for
damage Entities and place Fire, after that you need to call the damge function manualy,
something like:

List<Entity> entities = lightningBolt.level.getEntities(this, new AABB(this.getX() - 3.0D, this.getY() - 3.0D, this.getZ() - 3.0D, this.getX() + 3.0D, this.getY() + 6.0D + 3.0D, this.getZ() + 3.0D), Entity::isAlive);

for(Entity entity : entities) {
	if (!net.minecraftforge.event.ForgeEventFactory.onEntityStruckByLightning(entity, this))
		entity.thunderHit((ServerLevel)lightningBolt.level, this);
	}
}

 

Okay thanks