title: how to insert into set without changing the equals and hashcode
body: <p>I'm looking for a suggestion.
  I have a <code>Person</code> class with String firstName and String lastName
  When  i'm tying to insert the list values with the same String like : </p>
  
  <pre><code>set.add(new Person("firstName","lastName"))
  
  set.add(new Person("firstName","lastName"))
  </code></pre>
  
  <p>The set doesn`t filter the objects and they still getting in the set.
  There is any suggestion to create set list without overriding the equales and hashcode functions?
  Maybe with guava or some groovy list?
  Thanks,
  Or.</p>