activitypub: fix LD context

ActivityPub through ActivityStreams 2.0 requires the use of the
expansion algorithm from JSON-LD 1.0 which is not able to handle nested contexts.

Fixes commit 21ab8e75ee, thanks to sn0w.

packages/backend/src/remote/activitypub/renderer/index.ts

@@ -46,13 +46,8 @@ export const renderActivity = (x: any): IActivity | null => {
 				},
 				// schema
 				schema: 'http://schema.org/',
-				PropertyValue: {
-					'@id': 'schema:PropertyValue',
-					'@context': {
-						'value': 'schema:value',
-						'name': 'schema:name',
-					},
-				},
+				PropertyValue: 'schema:PropertyValue',
+				value: 'schema:value',
 				// Misskey
 				misskey: 'https://misskey-hub.net/ns#',
 				'_misskey_quote': {

packages/backend/src/remote/activitypub/renderer/person.ts

@@ -24,6 +24,7 @@ export async function renderPerson(user: ILocalUser) {
 	const attachment: {
 		type: 'PropertyValue',
 		name: string,
+		'schema:name': string,
 		value: string,
 		identifier?: IIdentifier
 	}[] = [];
@@ -44,6 +45,15 @@ export async function renderPerson(user: ILocalUser) {
 			attachment.push({
 				type: 'PropertyValue',
 				name: field.name,
+				// uses "name" for backward compatibility, but JSON-LD-expanding
+				// it ends up being the ActivityPub name property, which is not
+				// correct for this type. which is why we also send the "correct"
+				// schema.org name property field, which would not be recognized
+				// by people just processing JSON-LD as JSON as allowed by the spec.
+				// it would be nicer to do this with JSON-LD context, but this is
+				// only possible when using JSON-LD 1.1 with nested contexts, but
+				// activitystreams 2.0 requires the JSON-LD 1.0 expansion algorithm.
+				'schema:name': field.name,
 				value,
 			});
 		}