It would be a useful method to be able to access via the spigot api to re-calculate lighting at a specific location. With mojang's rework of the lighting engine, there is an easy way to access the method via NMS so it shouldn't be a big burden to add to the spigot API.

The following is how to do it via NMS

public void updateLighting(Location location) {
    net.minecraft.server.v1_16_R2.World nmsWorld = ((CraftWorld) world).getHandle();
    nmsWorld.e().a(new BlockPosition(location.getBlockX(), location.getBlockY(), location.getBlockZ()));
}

with nmsWorld.e() getting you the lightingEngine object and lightingEngine.a(BlockPostion) marking that position to be re-calculated.