title: stream and filter data in a sublist contained in a list
body: <p>I have a collection of authors <code>LinkedList&lt;Author&gt; autoren</code>, and a collection of books <code>List&lt;Book&gt; buecher</code>. The connection between a book and its author is the email address of the author.</p>
  
  <p>The Book class has a <code>Set</code> of authors' email addresses: <code>private Set&lt;String&gt; autoren</code>.</p>
  
  <p>For each book, I want to get the corresponding author-authors and print the last name and first name of the author.</p>
  
  <pre><code>LinkedList&lt;Author&gt; autoren = (LinkedList&lt;Autor&gt;) dataController.getAutoren().stream()
          .filter(s -&gt; buch.getAutoren().contains(s.getEmailadresse()));
  
  for (Author author: autoren) {
      sysout(auther.getName())
  }
  </code></pre>
  
  <p>my data model for bool looks like </p>
  
  <pre><code>public class Buch {
  
  private String title;
  
  private String isbnNummer;
  
  private Set&lt;String&gt; autoren;}
  </code></pre>
  
  <p>How can I get a list of all authors of all books, and filter by book name, using a lambda expression?</p>