title: Comparator.comparing(...) of a nested field
body: <p>Suppose I have a domain model like this:</p>
  
  <pre><code>class Lecture {
       Course course;
       ... // getters
  }
  
  class Course {
       Teacher teacher;
       int studentSize;
       ... // getters
  }
  
  class Teacher {
       int age;
       ... // getters
  }
  </code></pre>
  
  <p>Now I can create a Teacher Comparator like this:</p>
  
  <pre><code>    return Comparator
              .comparing(Teacher::getAge);
  </code></pre>
  
  <p>But how do I compare Lecture's on nested fields, like this?</p>
  
  <pre><code>    return Comparator
              .comparing(Lecture::getCourse::getTeacher:getAge) 
              .thenComparing(Lecture::getCourse::getStudentSize);
  </code></pre>
  
  <p>I can't add a method <code>Lecture.getTeacherAge()</code> on the model.</p>