Hello. I added a cauldron in minecraft with my mod and seems that it does not support the clay bucket. I looked into your ItemClayBucket class, and i wrote a code similiar to yours in interactCauldron in a FillBucketEvent. I have a question. I actually cant get the private methods used to place water in world with the clay bucket. I hope my text is clear. Thanks for reading.
Bye.

You should really not do this the way my bucket interacts with the cauldron, ideally what you should do is make your custom cauldron act as a fluid tank (one that only returns water of course). This will make it compatible with any mod adding a custom bucket instead of just mine. See this example from Inspirations (fluid handler class).

If your custom cauldron does not have a tile entity, your next good solution is to make it generic to fluid containers in your onBlockActivated method. LeatherWorks has a good example

Thank you for your reply.