[REQ] Add path of moustache file used to generated source file

Is your feature request related to a problem? Please describe.

I am new to OpeAPITools but have quite a bit of Java experience. I am looking into how the spring boot Api files have their sample return values generated. It has taken a very long time to find out that it came from "api.moustache" and then again additional time to find out which one to use. The folder "JavaSpring" is only intuitive if you know already.

If the relative path of api.moustace had been in a comment in the top of the file, that would have helped a lot.

Describe the solution you'd like

A comment in each source file saying "Generated from ..../../../api.moustache"

Alternatively the text output for each when the maven plugin runs would state which template had been used for generating that file.

Describe alternatives you've considered

So far I had to identify that each source file is written by TemplateManager.writeToFile and set a conditional break point using filename.endsWith and then navigate up the stack to look into variables to find the name of the directory used.

Additional context

Start at TemplateManager.writeToFile and trace how the JavaSpring api.moustache template is selected and how generated source files are written. Compare the two proposed approaches: adding the template path to generated-file comments or reporting it when the Maven plugin runs. Done means the template used for each generated file is discoverable without debugger-based stack inspection.