Empty Lists in JSON Templater

I am trying to figure out how to insert empty lists into a JSON Templator as an empty bracket like this:

"materials" : [],

Currently, I can't only get it to look like this:

"materials" : [

{

"materialBridgeId" : null,

"materialTypeName" : null,

"materialName" : null,

"quantity" : null,

"tamsUnitOfMeasureId" : null,

"tamsUnitOfMeasureName" : null,

"tamsStockpileId" : null,

"tamsStockpileName" : null,

"isDerivedFromCirus" : null

}

],

Any thoughts on I can achieve the empty elements listed above?

Thanks!

Mark