title: Apex (Salesforce) read json from response and store it in a string variable
body: <p>I am trying to hit a API endpoint which is responding something like below when I am calling 
  response.getBody()</p>
  
  <p>{
   "oktaToken": "eyJraWQiOiIyNlN1NHFMNnVVZTVJX2M5X2Z3WmZvX09ON0dNUHRtQzlEeHFsTGplLS00IiwiYWxnIjoiUlMyNTYifQ.eyJ2ZXIiOjEsImp0aSI6IkFULlVINmdIOF9BcWJ"
  }</p>
  
  <p>Now I wanted to store the value of this token into a string variable.</p>
  
  <p>response.getbody() is already a string but I want the value to be stored in a String variable. I don't wanted to do any manipulation in the String (response.getbody()) like splitting &amp; substring.</p>
  
  <p>Is there something using json parsing so That I can get the value of token in a variable by passing the key('oktaToken')?</p>