feat: add CompositeKey message and composite_key field to FeatureView…

…DataKey

PiperOrigin-RevId: 609467767

google/cloud/aiplatform/v1/feature_online_store_service.proto

@@ -73,9 +73,20 @@ enum FeatureViewDataFormat {
 
 // Lookup key for a feature view.
 message FeatureViewDataKey {
+  // ID that is comprised from several parts (columns).
+  message CompositeKey {
+    // Parts to construct Entity ID. Should match with the same ID columns as
+    // defined in FeatureView in the same order.
+    repeated string parts = 1;
+  }
+
   oneof key_oneof {
     // String key to use for lookup.
     string key = 1;
+
+    // The actual Entity ID will be composed from this struct. This should match
+    // with the way ID is defined in the FeatureView spec.
+    CompositeKey composite_key = 2;
   }
 }