Echoing a function in a namespace

What is the proper format for using namespaced functions in a dynamic data echo?

I tried ‘namespace\function’ and ‘\namespace\function’. Some actual examples:

{echo:JWR_Customizations\includes\common\reviews::convert_rating}
{echo:\JWR_Customizations\includes\common\reviews::convert_rating}

When I do the code review, it treats the namespace as the function and ignores the rest (the actual function name). It wanted me to whitelist the “function”: JWR_Customizations