Message Start Event variable=Json Object

Hello.
Is it possible to set a JSON object as value of variable, and then read it as Object?
I found a documentation about JSON, but in that reference we set variable in JavaDelegate and after that read it in next process.
But how can I read variable at the first step?

This is my JSON:
{
“messageName” : “CustomerRelationApprovalRequest”,
“businessKey” : “second 8”,
“resultEnabled”: “true”,
“processVariables”:{
“customer”: {
“value” : “{"name" : "Test Customer","id" : "1111111"}”,
“type” : “Json”
}
}
}