The pre-release 2 is all about emptiness and blankness...
FAPI v0.81.2 was released. No breaking change.
Ingredients may be an air to indicate empty slot. If your code uses Ingredient#fromJson, then it will automatically allow air ingredients. To keep old behavior of disallowing air ingredients (which you probably want), use fromJson overload with the boolean param set to false.
All uses of StringUtils#isBlank are swapped to Util#isBlank. This treats certain non-breaking spaces as blank.
ServerCommandSource#sendFeedback now takes Supplier<Text> instead of Text for performance reasons. Add () -> and it should be good to go.
Entity#isOnRail: returnstrueif the entity is a minecart on a rail.ChunkHoldermethods that send packets now take the list of players instead of querying watching players.ServerWorld#getRandomSequencesto get the random sequences.CommandBlockExecutor#isEditableto query if a command block can be edited.