Need help with loadYamlContent

[kpanugan]

I am seeing the following issue when using loadYamlContent function in bicep file
var bicepObject = loadYamlContent('testVal.yaml')
output helloWorld object = bicepObject

where input is something simple

TopValues:
 labels:
   -keyName: "null"

The outputs i was expecting was

{
   "TopValues":{
     "labels":[{
        "keyName":"null"
     }]
    }
}

but i am getting it as

{
   "TopValues":{
     "labels":[{
        "keyName": null
     }]
    }
}

why is the value for "keyName" getting converted to a null instead of string which has null