not sure if I understand all your questions, but to clarify:
In our context PROTOTYPING=true is a system environment variable  for which the running operating system accounts responsible. You can set such environment variables in multiple ways and note, this does not require Docker!
Also note: mvn -Dkey=value does not set an environment variable (this does set a system property, which is specific to the Java runtime)
Does this answer your questions and concerns?
On 2018/10/29 04:41:40, Brian K <[EMAIL PROTECTED]> wrote: