{
    "version" : "2017-02-28",
    "operation" : "PutItem",
    "key": {
        "userId": { "S" : "${context.arguments.userId}"},
		"conversationId": { "S" : "${context.arguments.conversationId}"}
    },
    "attributeValues" : {
        "userId": {  "S": "${context.arguments.userId}" },
		"conversationId": {  "S": "${context.arguments.conversationId}" }
    }
}