what I expected:
sponge will dry and put water in the STACK of buckets and give 16 water buckets.

what actually happened:
sponge dries and destroys/removes buckets leavin only one water bucket

possible ways to solve this:

• only restrict the furnace having only ONE bucket in the bottom slot at max
• Not filling the buckets at all
• filling all 16
• drop the filled water bucket from the furnace
• have an extra slot in the furnace