Dynamic date REST parameter?

Is there any way to define a REST parameter that will automatically take like tomorrow's date?

I tried this, but don't know what's really possible or what the syntax would be for more complicated steps:

${=import java.util.Calendar; Calendar now=Calendar.getInstance(); now = now.add(Calendar.DATE, 1); new java.text.SimpleDateFormat("yyyy-MM-dd").format(now.getTime())}

According to the raw value, "now" is null when now.getTime() is called.