Spring boot: JSON parameter starting with special character

I'm using Spring Boot for a REST Server, but I would like to have some of the parameter of the json string using special character as bellow (_id, $oid):

 "data": [
    {
      "_id": {
        "$oid": "122121b1212v2aa99898ee"
      },

Is this possible?
When defining the Class which has the elements I'm not able to define variables using this special characters...

Thanks in advance.