I recently found out that there is Entity#playEffect(EntityEffect.GUARDIAN_TARGET) to show Guardian's laser when the Guardian has a target.

However, it turns out that when the awareness is disabled with Guardian#setAware(false), then it's not possible to set target for the guradian with Guardian#setTarget(livingEntity) for some reason. This is true for Spigot 1.16.x also.

To work around this issue, I am able to set the target by using DataWatcher:

DataWatcher dataWatcher = ((CraftLivingEntity) guardian).getHandle().getDataWatcher();
dataWatcher.set(new DataWatcherObject<>(16, DataWatcherRegistry.b), targetEntityId);  // https://wiki.vg/Entity_metadata#Guardian -> Target EID -> 16

guardian.playEffect(EntityEffect.GUARDIAN_TARGET);

This forces me to use a version-dependant solution... Is it an oversight or is it intended that the target cannot be manually set while the awareness is disabled and/or I could approach it differently?