title: How to solve lint warning "field is never used" but it is serialized
body: <p>I have a small class in my Android project containing some variables,  I assign them in the constructor.</p>
  
  <p>I then serialize the object to json using the Gson library and the function <code>String Gson::toJson(Object src)</code> </p>
  
  <p>How can I solve this lint warning : "private field is assigned but never accessed" on these variables? Is there a special comment for that case? </p>
  
  <p>edit : sorry there is another warning too "Field can be converted to a local variable" which is wrong!</p>
  
  <p>Thank you!</p>