Anvils, grindstones, brewing stands, stonecutters, lanterns, beds, lecterns, composters, hoppers, and enchantment tables are not waterlog-able. The water cannot be placed into the block and instead acts like its a full block and places it on it. 

To replicate, take a water bucket and shift right click on any of these blocks ^ or click on the block next to it but on the interior facing any of ^ blocks.