Merge 339ea6be12 into 65b1db721d

We seem to have [updated this for m.room.name](https://github.com/matrix-org/matrix-spec/pull/1639) some years back but omitted it for topic.

changelogs/client_server/newsfragments/2068.clarification

@@ -0,0 +1 @@
+Clarify behaviour when the `topic` key of a `m.room.topic` event is absent, null, or empty.

changelogs/client_server/newsfragments/2077.clarification

@@ -0,0 +1 @@
+Fix the example of the `GET /sync` endpoint and the `m.room.member` example used in several places.

changelogs/client_server/newsfragments/2109.clarification

@@ -0,0 +1 @@
+Spaces are subject to the same access mechanisms as rooms.

content/client-server-api/modules/spaces.md

@@ -2,8 +2,8 @@
 
 {{% added-in v="1.2" %}}
 
-Often used to group rooms of similar subject matter (such as a public "Official
+Often used to group rooms of similar subject matter (such as an "Official
-matrix.org rooms" space or personal "Work stuff" space), spaces are a way to
+matrix.org rooms" space or a "Work stuff" space), spaces are a way to
 organise rooms while being represented as rooms themselves.
 
 A space is defined by the [`m.space` room type](#types), making it known as a
@@ -19,10 +19,10 @@ go a step further and explicitly ignore notification counts on space-rooms.
 
 Membership of a space is defined and controlled by the existing mechanisms which
 govern a room: [`m.room.member`](#mroommember), [`m.room.history_visibility`](#mroomhistory_visibility),
-and [`m.room.join_rules`](#mroomjoin_rules). Public spaces are encouraged to have
+and [`m.room.join_rules`](#mroomjoin_rules). Canonical aliases and invites, including
-a similar setup to public rooms: `world_readable` history visibility, published
+third-party invites, still work just as they do in normal rooms as well. Furthermore,
-canonical alias, and suitably public `join_rule`. Invites, including third-party
+spaces can also be published in the [room directory](#room-directory) to make them
-invites, still work just as they do in normal rooms as well.
+discoverable.
 
 All other aspects of regular rooms are additionally carried over, such as the
 ability to set arbitrary state events, hold room account data, etc. Spaces are
@@ -87,10 +87,9 @@ the state of `#space:example.org` would consist of:
 }
 ```
 
-No state events in the child rooms themselves would be required (though they
+No state events in the child rooms themselves would be required (though they can also
-can also be present). This allows for users
+be present). This allows for users to define spaces without needing explicit permission
-to define personal/private spaces to organise their own rooms without needing explicit
+from the room moderators/admins.
-permission from the room moderators/admins.
 
 Child rooms can be removed from a space by omitting the `via` key of `content` on the
 relevant state event, such as through redaction or otherwise clearing the `content`.

data/api/client-server/sync.yaml

@@ -441,17 +441,57 @@ paths:
                           "state": {
                             "events": [
                               {
-                                "$ref": "../../event-schemas/examples/m.room.member.yaml"
+                                "content": {
+                                  "avatar_url": "mxc://example.org/SFHyPlCeYUSFFxlgbQYZmoEoe",
+                                  "displayname": "Example user",
+                                  "membership": "join"
+                                },
+                                "event_id": "$143273976499sgjks:example.org",
+                                "origin_server_ts": 1432735824653,
+                                "sender": "@example:example.org",
+                                "state_key": "@example:example.org",
+                                "type": "m.room.member",
+                                "unsigned": {
+                                  "age": 45603,
+                                  "membership": "join"
+                                }
                               }
                             ]
                           },
                           "timeline": {
                             "events": [
                               {
-                                "$ref": "../../event-schemas/examples/m.room.member.yaml"
+                                "content": {
+                                  "avatar_url": "mxc://example.org/SEsfnsuifSDFSSEF",
+                                  "displayname": "Alice Margatroid",
+                                  "membership": "join",
+                                  "reason": "Looking for support"
+                                },
+                                "event_id": "$143273582443PhrSn:example.org",
+                                "origin_server_ts": 1432735824653,
+                                "sender": "@alice:example.org",
+                                "state_key": "@alice:example.org",
+                                "type": "m.room.member",
+                                "unsigned": {
+                                  "age": 1234,
+                                  "membership": "join"
+                                }
                               },
                               {
-                                "$ref": "../../event-schemas/examples/m.room.message$m.text.yaml"
+                                "content": {
+                                  "body": "This is an example text message",
+                                  "format": "org.matrix.custom.html",
+                                  "formatted_body": "<b>This is an example text message</b>",
+                                  "msgtype": "m.text"
+                                },
+                                "event_id": "$143273582443PhrSn:example.org",
+                                "origin_server_ts": 1432735824653,
+                                "sender": "@example:example.org",
+                                "type": "m.room.message",
+                                "unsigned": {
+                                  "age": 1234,
+                                  "membership": "join"
+                                }
                               }
                             ],
                             "limited": true,

data/event-schemas/examples/m.room.member.yaml

@@ -1,6 +1,7 @@
 {
   "$ref": "core/state_event.json",
   "state_key": "@alice:example.org",
+  "sender": "@alice:example.org",
   "type": "m.room.member",
   "content": {
     "membership": "join",

data/event-schemas/schema/m.room.topic.yaml

@@ -1,7 +1,14 @@
 ---
 allOf:
   - $ref: core-event-schema/state_event.yaml
-description: 'A topic is a short message detailing what is currently being discussed in the room.  It can also be used as a way to display extra information about the room, which may not be suitable for the room name. The room topic can also be set when creating a room using `/createRoom` with the `topic` key.'
+description: |- 
+    A topic is a short message detailing what is currently being discussed in the room.
+    It can also be used as a way to display extra information about the room, which may not
+    be suitable for the room name.
+    The room topic can also be set when creating a room using `/createRoom` with the `topic` key.'
+    
+    If the `topic` property is absent, null, or empty then the topic is unset. In other words,
+    an empty `topic` property effectively resets the room to having no topic.
 properties:
   content:
     properties: