Copper Golem head object is stored as item, displayed as block

As of 25w33a things can now be displayed on top of a copper golem’s head. However, while they are displayed as blocks, they are handled as items, which is very inconsistent with other entities and has undesirable side effects.

For example:

• most items will be completely invisible on a copper golem, as they have no direct block equivalent

• even for items which do have a block equivalent, the states of that block cannot be customized

For comparison to endermen and minecarts, which do indeed display blocks and carry their actual IDs:

• /summon minecraft:enderman ~ ~ ~ {carriedBlockState:{Name:"minecraft:redstone_wire"},NoAI:1}

• /summon minecraft:minecart ~ ~ ~ {CustomDisplayTile:1b,DisplayState:{Name:"minecraft:redstone_wire"},DisplayOffset:16}

• /summon minecraft:copper_golem ~ ~ ~ {equipment:{head:{id:"minecraft:redstone_wire"}},NoAI:1b}

• /summon minecraft:copper_golem ~ ~ ~ {equipment:{head:{id:"minecraft:redstone"}},NoAI:1b}

The first two commands work as expected, respectively summoning an enderman and minecart displaying a redstone wire piece. The third command does not work: a copper golem is summoned with nothing on its head. The fourth command summons a copper golem with redstone wire on its head like the first two commands, but note how the item ID had to be specified instead of the block ID.

Note also how for the first two, block states can be specified, which is impossible for copper golems:

• /summon minecraft:enderman ~ ~ ~ {carriedBlockState:{Name:"minecraft:redstone_wire",Properties:{north:"up"}},NoAI:1}

• /summon minecraft:minecart ~ ~ ~ {CustomDisplayTile:1b,DisplayState:{Name:"minecraft:redstone_wire",Properties:{north:"up"}},DisplayOffset:16}

How to fix: instead of handling the thing on top of a copper golem’s head as head slot equipment, a dedicated “head block state” field could be introduced, which allows specifying a block ID and state as is done for endermen, minecarts, falling blocks, TNT entities, and block displays. Alternatively, the copper golem’s head slot item could render as an item model rather than a block model, making it consistent with all other entities that render head items.