Added type hint to load_custom_writeObject

incomplete to avoid circular import

Author: tcalmant

javaobj/v2/api.py

@@ -80,6 +80,7 @@ def load_array(self, reader, type_code, size):
         return None
 
     def load_custom_writeObject(self, parser, reader, name):
+        # type: (JavaStreamParser, DataStreamReader, str) -> Optional[list]
         """
         Reads content stored from a custom writeObject.