deserialize with JMS Serializer

[sela]

I'm using JMS Serializer and try to deserialize JSON Point coordinates.
I wasn't sure for the format so serialized an object and got the following format (coordinate is the column name):

{
    "coordinate": {
        "x": 12.0,
        "y": 12.0
    }
}

now I try the same from JSON and the deserialize fails with the message: You must define a type for App\Entity\Something::$coordinate.