JSON Syntax: LoggerConfig - multiple AppenderRef entries

How does one assign multiple AppenderRef entries to a logger when using JSON syntax? I've tried numerous formats but none of them appear to work. Exampe below.

"loggers": {
"logger": [
{
"name": "helloWorld",
"level": "info",
"additivity": "true",
"AppenderRef": [

{ "ref": "File Routing Appender" }

,

{ "ref": "Database Routing Appender" }

]
}
],
"root": {
"level": "info",
"AppenderRef":

{ "ref": "Console Appender" }

}
}

2013-12-11 08:32:07,012 DEBUG Calling createLogger on class org.apache.logging.log4j.core.config.LoggerConfig for element logger with params(additivity="true", level="info", name="helloWorld", includeLocation="null", AppenderRef={}, Properties={}, Configuration(Hello World Config), null)

The only way I've been able to hack this (up to a maximum of two AppenderRefs) is to use the appender-ref alias in conjunction with AppenderRef e.g.:
"loggers": {
"logger": [

{
"name": "helloWorld",
"level": "info",
"additivity": "true",
"AppenderRef":

{ "ref":"File Routing Appender" }

,
"appender-ref":

{ "ref":"Database Routing Appender" }

}
],
"root": {
"level": "info",
"AppenderRef":

{ "ref": "Console Appender" }

}
}
2013-12-11 08:51:54,977 DEBUG Calling createLogger on class org.apache.logging.log4j.core.config.LoggerConfig for element logger with params(additivity="true", level="info", name="helloWorld", includeLocation="null", AppenderRef=

{File Routing Appender, Database Routing Appender}

, Properties={}, Configuration(Hello World Config), null)