Right now you can set a string using content, but since hiera can't interpolate the puppet 'file' function, you can not set a new flat file in a profile and pass that profile module's file location to the content string properly.
Would be nice to support this so that you don't have to worry about literal formatting your banner in hiera directly, or use a collector or something crazy like that.
This is already supported using the built-in file function piped into content.
After digging through this again, I realized why I opened it in the first place. You can't use the file function from hiera data directly and since this is an included class via profile you can only set `issue::content` as a string or an interpolation function. This doesn't allow setting another file without a full class instantiation of issue.
We should indeed create a separate source option.