title: how to use codegen in swagger to create server side code in php
body: <p>I am creating API documentations for my APIs. while creating am stuck in a problem that :
  I want to generate server side code for my API by which user can easily implement that code. I read about "codegen" by swagger by which one can generate code in different languages. So any please suggest me how to use that feature to generate code in different language (java,php...). or any alternative for this. also Guide me if i am wrong at any point of view. 
  Thanks in advance.</p>