[fork] client-api: Re-add the MSC3440 related_by_* room event filters.

These fields were removed by MSC3856 but the filtering they describe is stable
since Matrix 1.4, so the fork carries them again. The io.element.* unstable
names are kept as deserialize aliases.

Signed-off-by: Jason Volk <jason@zemos.net>

Author: jevolk

crates/ruma-client-api/CHANGELOG.md

@@ -19,6 +19,10 @@ Improvements:
   `unstable` to `v1`, and the retained unstable endpoint shares the v1
   request and response types; the response fields are now `joined`, `count`
   and `next_batch`.
+- Add the `related_by_rel_types` and `related_by_senders` fields to
+  `RoomEventFilter`, to filter room events by their relations as stabilized
+  in Matrix 1.4 (MSC3440). The `io.element.relation_types` and
+  `io.element.relation_senders` unstable names are accepted as aliases.
 
 Bug fixes:
 

crates/ruma-client-api/src/filter.rs

@@ -101,6 +101,24 @@ pub struct RoomEventFilter {
     /// [`sync_events`]: crate::sync::sync_events
     #[serde(default, skip_serializing_if = "ruma_common::serde::is_default")]
     pub unread_thread_notifications: bool,
+
+    /// A list of relation types to include.
+    ///
+    /// An event A is included in the filter only if there exists another event B which relates to
+    /// A with a `rel_type` which is defined in the list.
+    #[serde(default, alias = "io.element.relation_types", skip_serializing_if = "<[_]>::is_empty")]
+    pub related_by_rel_types: Vec<String>,
+
+    /// A list of senders to include.
+    ///
+    /// An event A is included in the filter only if there exists another event B which relates to
+    /// A, and which has a sender which is in the list.
+    #[serde(
+        default,
+        alias = "io.element.relation_senders",
+        skip_serializing_if = "<[_]>::is_empty"
+    )]
+    pub related_by_senders: Vec<OwnedUserId>,
 }
 
 impl RoomEventFilter {
@@ -140,6 +158,8 @@ impl RoomEventFilter {
             && self.url_filter.is_none()
             && self.lazy_load_options.is_disabled()
             && !self.unread_thread_notifications
+            && self.related_by_rel_types.is_empty()
+            && self.related_by_senders.is_empty()
     }
 }