Add sign_empty method to EventSigner protocol

Author: alexgromero

packages/smithy-core/.changes/next-release/smithy-core-enhancement-857985c5f3a848ddbab3179678a57aa8.json

@@ -0,0 +1,4 @@
+{
+  "type": "enhancement",
+  "description": "Added sign_empty method to EventSigner protocol for signing empty events."
+}

packages/smithy-core/src/smithy_core/aio/interfaces/auth.py

@@ -31,6 +31,17 @@ async def sign(self, *, event: Any, identity: I, properties: SP) -> Any:
         """Get a signed version of the event.
 
         :param event: The event to be signed.
+        :param identity: The identity to use to sign the event.
+        :param properties: Additional properties used to sign the event.
+        """
+        ...
+
+    async def sign_empty(self, *, event: Any, identity: I, properties: SP) -> Any:
+        """Get a signed version of an empty event.
+
+        :param event: The empty event to be signed.
+        :param identity: The identity to use to sign the event.
+        :param properties: Additional properties used to sign the event.
         """
         ...