Incomplete registration of entities for Item data conversion

Certain entities store an "Item" value in their NBT saving. This field is not registered with the entity in the DataConverter Schemas. This issue has probably not manifested itself yet due to the unlikeliness of these entities to save and exist for conversion. Thus, this issue report is an fyi to something that should be fixed for completeness sake in the future.

Specifically. In the schema numbered 1460. The following entities are lacking  an "Item" field registration.

• minecraft:eye_of_ender_signal (since renamed to minecraft:eye_of_ender)
• minecraft:xp_bottle (since renamed to minecraft:experience_bottle)
• minecraft:snowball
• minecraft:ender_pearl
• minecraft:egg
• minecraft:small_fireball

I don't know if these fields are even used by the entity. Just making a code observation.