title: Vaadin ComboBox with values and IDs
body: <p>I have defined a <code>ComboBox</code> which allows the user to select a contact from his contact list. The ComboBox is showing the contact name, but that can not really be used to map to the real contact: the contact ID is needed. My problem is that I do not know how to populate the <code>Vaadin</code> <code>ComboBox</code> with linked values and IDs, but only showing the values.</p>
  
  <pre class="lang-java prettyprint-override"><code>// Add all organization contacts to the drop-down
  for (Contact contact : organizationContacts) {
      contactName = contact.getName();
      contactId   = contact.getId();
      _logger.debug("Adding contactName=" + contactName + " contactId=" + contactId + " to person with id=" + personId);
      contactNameCombo.addItem(contactName);
  }
  
  // Add the contact of this person, and select it in the drop-down
  contactName = person.getContact().getName();
  contactId   = person.getContact().getId();
  contactNameCombo.addItem(contactName);
  contactNameCombo.setValue(contactName);
  </code></pre>
  
  <p>As you can see in the code above, I am adding the <code>contactName</code> to the <code>ComboBox</code>, but I do not know how to add also the <code>contactId</code> so that I can know later, from the selected entry, which ID must be used to update the database.</p>