Json layout - message woth custom keyvalue pairs

[sambir]

With the JsonLayout the logging message is being displayed as a string with
"messages" key as below.

 "message" :
"{\"ReqId\":\"12345\",\"appName\":\"1_APP\",\"actionName\":\"PUT
operation\"}",

Is it possible to write the individual fields as key/value pair on its own?
Please let me know how we can customize the json layout for this.

"ReqId" : "12345",
"appName" : "1_APP",
"actionName" : "PUT operation"

This is the complete log message for reference:

{

  "timeMillis" : 1483466765852,

  "thread" : "main",

  "level" : "INFO",

  "loggerName" : "com.capitalone.cerberus.logging.JsonTest",

  "message" :
"{\"ReqId\":\"12345\",\"appName\":\"1_APP\",\"actionName\":\"PUT
operation\"}",

  "endOfBatch" : false,

  "loggerFqcn" : "org.apache.logging.log4j.spi.AbstractLogger",

  "threadId" : 1,

  "threadPriority" : 5,

  "source" : {

    "class" : "com.capitalone.cerberus.logging.JsonTest",

    "method" : "main",

    "file" : "JsonTest.java",

    "line" : 17

  }

}