code: function formatJsonTrace(level, context, message, args, err) {
    return formatJsonTrace.stringify(formatJsonTrace.toObject(level, context, message, args, err));
  }
docs: Formats a trace message in JSON format
  
  @param {String} level One of the following values
  ['DEBUG', 'INFO', 'WARN', 'ERROR', 'FATAL']
  @param {Object} context Additional information to add to the trace
  @param {String} message The main message to be added to the trace
  @param {Array} args More arguments provided to the log function
  @param {Error|null} err A cause error used to log extra information
  
  @return {String} The trace formatted