Required, either-or properties

[Russell Bateman]

How are folk specifying processor properties in the case where one of 
two properties is required, but not both? I'm just wondering if there's 
a best practice here or must I say something in the description?

For example, I've written a processor that implements Apache Velocity 
templating. I require the template content be passed either directly as 
the value of a property, "Template content", or a filesystem path to 
this content in a property, "Template filepath".