Synchronize new proto changes.
diff --git a/google/spanner/v1/spanner_gapic.yaml b/google/spanner/v1/spanner_gapic.yaml
index bdf3378..86be71a 100644
--- a/google/spanner/v1/spanner_gapic.yaml
+++ b/google/spanner/v1/spanner_gapic.yaml
@@ -82,6 +82,26 @@
     field_name_patterns:
       name: session
     timeout_millis: 30000
+  - name: ListSessions
+    flattening:
+      groups:
+      - parameters:
+        - database
+    required_fields:
+    - database
+    request_object_method: true
+    page_streaming:
+      request:
+        page_size_field: page_size
+        token_field: page_token
+      response:
+        token_field: next_page_token
+        resources_field: sessions
+    retry_codes_name: idempotent
+    retry_params_name: default
+    field_name_patterns:
+      database: database
+    timeout_millis: 30000
   - name: DeleteSession
     flattening:
       groups: