How to pass object as string when delivering message to process

Hi Team,

I have to send message to process instance to complete the task. I am using below rest api and json request and giving error. Please let me know how i can pass localtime object in request.

API:
https://xxxxxx/xxxxxx/engine-rest/message

Request :
{“messageName” : “date_completed”,
“businessKey” : “123456”,
“processInstanceId” : “xxx-xx-xxxxx-xxxxxx”,
“processVariables” : {
“requestedNewActivationDate” : {“value” : “2021-11-27”, “type”: “Object”}
}
}

Response:

{
“type”: “ProcessEngineException”,
“message”: “Cannot find serializer for value ‘ObjectValue [value=null, isDeserialized=false, serializationDataFormat=null, objectTypeName=null, serializedValue=35 chars, isTransient=false]’.”
}

Regards,
Nagendra.