title: Finding duplicated objects by two properties
body: <p>Considering that I have a list of Person objects like this :</p>
  
  <pre><code>Class Person {
    String fullName;
    String occupation;
    String hobby;
    int salary;
  }
  </code></pre>
  
  <p>Using java8 streams, how can I get list of duplicated objects only by fullName and occupation property? </p>