minecraft-packets/minecraft-packets/data/pc/1.12.2/from-server/entity_update_attributes/1.json

An easy way to query PrismarineJS/minecraft-packets

{
  "entityId": 837,
  "properties": [
    {
      "key": "generic.movementSpeed",
      "value": 0.10000000149011612,
      "modifiers": []
    }
  ]
}