Zombie horses, skeleton horses, zombie nautiluses and camel husks are not targeted by the conduit in Java Edition, this is inconsistent with all other monsters and with Bedrock Edition.
Steps to reproduce the issue:
Build a conduit, have one of the above mentioned mobs in the water or rain, they are not targeted.
Expected result:
The conduit should damage them since they are monsters.
Actual result:
Nothing happens, as the conduit ignores them.
They are passive, the issue is in Bedrock Edition, conduits don't attack undead because of being undead, attack hostile water mobs like guardians