How to escape a variable in XL-Release

Question

Our XL-Release pipeline has placeholders with strings destined for an NLog config. NLog configs have syntax that support interpolated values using the same syntax as XL-Release uses for variables: ${variablename}. For example, in NLog ${basedir} equates to the base directory and ${shortdate} gives a current timestamp string.

Unfortunately, XL-Release does a variable lookup on these values, finds nothing and replaces the intended NLog config text with nothing.

Is there a way to escape the NLog values so that XL-Release leaves them alone? Perhaps a backslash?: \${variablename}.

Fo example, our lookup dictionary has an entry like so:

"App": {
  "ProgramName": {
    "ArchiveFilename": "${basedir}/logs/archive/ProgramName-${shortdate}.log",
    "Filename": "${basedir}/logs/ProgramName.log"
  },
etc...

The template looks like this:

<targets>
    <target name="logfile" xsi:type="File" fileName="{{ App.ProgramName.Filename }}"

And, instead of getting this:

<targets>
    <target name="logfile" xsi:type="File" fileName="${basedir}/logs/ProgramName.log"

I get this (XL-Release having dropped ${basedir}):

<targets>
    <target name="logfile" xsi:type="File" fileName="/logs/ProgramName.log"

How can I escape ${basedir} so XL-Release doesn't replace it?