Ignores 'required' tag in model.mustache in python

[vishalsanfran]

Description

Swagger ignores 'required' tag in model.mustache in python.
The setter function for these properties does not allow null values, unlike ruby and other languages

Swagger-codegen version

2.2.1 (latest)

Steps to reproduce

1. Required is false

"license":
{"type":"string","description":"license key", required: false}

Expected output:
@license.setter
def license(self, license):
self._license = license

2. Required is true
   "license":
   {"type":"string","description":"license key", required: true}

Expected output:
@license.setter
def license(self, license):
if not license:
raise ValueError("Invalid value for license, must not be None")
self._license = license

Currently, output is always 2) whether 'required' is true or false

Suggest a Fix

Its a simple 2 line fix, very similar to the ruby code
i'll submit it

[wing328]

PR merged into master. Thanks for the contribution.