This is one of many protocol behaviors described in ActivityPub.

Identifier

urn:uuid:c1cd98fe-ae9c-48a7-9b43-cdd8eb008bc8

Content

the object MUST be modified to reflect the new structure as defined in the update activity

Origin

prefix The Update activity is used when updating an already existing object.

The side effect of this is that the object MUST be modified to reflect the new structure as defined in the update activity, assuming the actor has permission to update this object.
 
suffix 6.3.1 Partial Updates

https://www.w3.org/TR/activitypub/

JSON

{
  "id": "urn:uuid:c1cd98fe-ae9c-48a7-9b43-cdd8eb008bc8",
  "uuid": "c1cd98fe-ae9c-48a7-9b43-cdd8eb008bc8",
  "type": "Behavior",
  "content": "the object MUST be modified to reflect the new structure as defined in the update activity\n",
  "context": [
    "https://www.w3.org/TR/activitypub/",
    {
      "name": "6. Client to Server Interactions",
      "id": "https://www.w3.org/TR/activitypub/#client-to-server-interactions"
    },
    {
      "name": "6.3 Update Activity",
      "id": "https://www.w3.org/TR/activitypub/#update-activity-outbox"
    }
  ],
  "origin": {
    "source": "https://www.w3.org/TR/activitypub/",
    "section": {
      "id": "https://www.w3.org/TR/activitypub/#update-activity-outbox",
      "name": "Update Activity",
      "branch": [
        6,
        3
      ]
    },
    "selector": {
      "type": "TextQuoteSelector",
      "prefix": "The Update activity is used when updating an already existing object.\n",
      "exact": "The side effect of this is that the object MUST be modified to reflect the new structure as defined in the update activity, assuming the actor has permission to update this object.\n",
      "suffix": "6.3.1 Partial Updates\n"
    }
  },
  "@context": [
    "https://www.w3.org/ns/activitystreams",
    "https://socialweb.coop/ns/testing/context.json"
  ]
}