title: Understanding java 8 lambda expressions used to define Spring Security beans
body: <pre><code>@Bean
      public AuthenticationEntryPoint unauthorizedEntryPoint() {
          return (request, response, authException) -&gt; response.sendError(HttpServletResponse.SC_UNAUTHORIZED);
      }
  </code></pre>
  
  <p>How to understand this <code>(request, response, authException) -&gt;</code>, Where did it find all these 3 variables? there are not in class field.</p>
  
  <p>And what is it  <code>-&gt;</code> ?</p>