add pure Java generator

[danthe1st]

Is your feature request related to a problem? Please describe.
Postman comes with a few code generators for HTTP Requests.

For Java devs, there are generators for the Libraries OkHttp and Unirest, but there is no code generator for Java without any libraries

Describe the solution you'd like
A new code generator generating java code (with URLs/HttpURLConnection and HttpsURLConnection).

Additional context
https://docs.oracle.com/javase/8/docs/api/java/net/URL.html
https://docs.oracle.com/javase/8/docs/api/java/net/HttpURLConnection.html
https://docs.oracle.com/javase/8/docs/api/javax/net/ssl/HttpsURLConnection.html

[someshkoli]

I'd like to work on this. Getting started for this

[NeetigyaPod]

Hi is this still up for grabs? I wish to contribute