This week's snapshot introduces experimental support for custom biomes in data packs. This work has involved redoing some of the internal plumbing of things behind the scene, so it might be a bit leaky. We hope no important parts drip out, but if they do, pick them back up for us, please.

As always, make sure to make backups if you try a world in a snapshot.

Changes in 20w28a

Villagers now emit green particles when joining a village, setting a home bed, or acquiring a job site/profession
Brewing stands can now be crafted with blackstone
Tweaked bartering loot
Totems of undying now give the fire resistance status affect for 40 seconds when activated

Technical Changes in 20w28a

Custom worlds now support custom biomes
Dedicated servers can now rate limit clients

Customized world generation

There is now experimental support for a worldgen folder in data packs
worldgen/biome can contain biome definitions
worldgen/configured_carver can contain definitions for world carver settings
worldgen/configured_feature can contain definitions for feature placements
worldgen/configured_structure_feature can contain definitions for structure placements
worldgen/configured_surface_builder can contain definitions for surfaces
worldgen/processor_list can contain sets of block processors
worldgen/template_pool can contain pool definitions for jigsaw structures
Custom biomes can now be used in the single biome/caves/floating islands world types (add the data pack containing the biome first)
Custom biomes can now be used in custom dimension generators

Dedicated server packet limit

Dedicated servers can now kick clients that consistently send too many packets within a second
Controlled with the rate-limit settings in server.properties
The default rate limit of 0 means "no limit"

Fixed bugs in 20w28a

MC-34661 Thorns enchantment causes double armor decay
MC-65953 Tags IsBaby and IsVillager can't be changed from true to false with /entitydata
MC-171363 Nether forest biomes: Large fungi and small plants only generate on the topmost layer of nylium, leaving all lower layers devoid of flora
MC-172221 Hoglins, zoglins, ravagers, iron golems, and polar bears won't walk down a block if they are partially walking on air
MC-173526 All Minecarts can survive in lava
MC-174479 Cannot place sea pickles on soul sand
MC-174520 Soul particle texture is incorrect for the first frame
MC-176753 Piglins stand around dropped golden items if their "CanPickUpLoot" tag is set to "0b"
MC-179369 Wandering Traders are always invisible in the Nether and the End
MC-181204 doDaylightCycle button slightly incorrectly labeled
MC-181233 Mobs cannot spawn on wooden trapdoors, but can on iron and nether fungus trapdoors
MC-182430 Piglins continuously try and fail to pick up gold ingots if they can't reach them
MC-182868 Rail updates are 4-5x times laggier since 1.14 if the rail is on top of a non-full cube
MC-185684 Enderman can teleport when hit in cases where they previously would not teleport
MC-185925 Casting issue: Mineral vein generation uses 32-bit floats, leading to precision loss and potential crashes
MC-187112 Extra space in "Keep Jigsaws" button in jigsaw block
MC-187126 Jigsaw block UI is not closed when pressing "Generate"
MC-187129 Jigsaw blocks do not generate the correct structure until "Done" is pressed and the UI is reopened
MC-188459 Potted cactus still missing cullface argument for top
MC-188534 Potted cactus missing bottom face
MC-189769 Fungi grows through fire
MC-190098 Structure size and offset still limited to 32 for dedicated servers
MC-190852 Advancement announcement message has switched brackets for right-to-left languages
MC-190856 '/list uuids' shows parentheses incorrectly for right-to-left languages
MC-190860 '/' (slash) in chat and command block shows legacy formatting symbol for right-to-left languages
MC-190891 Certain redstone circuits causing lag
MC-190892 Brackets in potion effects are reversed in right-to-left languages
MC-191501 Opening a world from earlier 1.14 releases in 1.16 causes villagers to vanish
MC-191571 Switched square brackets for right-to-left languages
MC-191579 Book signing GUI has broken formatting for right-to-left languages
MC-191656 Right-to-left languages don't perform as expected in creative search menu
MC-192306 Crimson and warped slabs use incorrect colors on maps
MC-193073 Game crashes when Piglins or Piglin Brutes convert to Zombified Piglins
MC-193089 Mobs do not get damaged anymore if they're in lava and water at the same time
MC-193125 Cannot use "Inventory" key to write in recipe book, it closes GUI instead (Default: "E")

Minecraft Snapshot 20w28a