title: Does Lombok toBuilder() method creates deep copy of fields
body: <p>I am using <code>toBuilder()</code> on an object instance to create a builder instance and then build method to create new instance. The original object has a list, does the new object has reference to same list or a copy of it?</p>
  
  <pre class="lang-java prettyprint-override"><code>@Getter
  @Setter
  @AllArgsConstructor
  public class Library {
  
      private List&lt;Book&gt; books;
  
      @Builder(toBuilder=true)
      public Library(final List&lt;Book&gt; books){
           this.books = books;
      }
  
  }
  
  </code></pre>
  
  <pre class="lang-java prettyprint-override"><code>Library lib2  = lib1.toBuilder().build();
  </code></pre>
  
  <p>Will lib2 books refer to same list as lib1 books ?</p>