Deprecate old admin API GET /_synapse/admin/v1/users/<user_id>

CHANGES.md

@@ -1,3 +1,20 @@
+Synapse 1.xx.0 (2021-xx-xx)
+===========================
+
+Removal warning
+---------------
+
+The old List Accounts API is deprecated and will be removed in a future release. They will be replaced by the
+[List Accounts API](https://github.com/matrix-org/synapse/blob/master/docs/admin_api/user_admin_api.rst#list-accounts).
+
+The new API is available since Synapse 1.7.0 (2019-12-13).
+
+The old API has no documentation and unit tests. It is misleading.
+It expects user_id and returns a list of all users.
+
+`GET /_synapse/admin/v2/users` replaces `GET /_synapse/admin/v1/users/<user_id>`.
+
+
 Synapse 1.27.0 (2021-02-16)
 ===========================
 

changelog.d/9429.removal

@@ -0,0 +1 @@
+Deprecate old admin API `GET /_synapse/admin/v1/users/<user_id>`.