title: Concat parameters from object list
body: <p>I have list of objects:</p>
  <pre><code>List&lt;Obj&gt; objList = [obj1, obj2]
  
  obj1.val = &quot;val1&quot;
  obj2.val = &quot;val2&quot;
  </code></pre>
  <p>And I want to concat String parameters from that objects with &quot;.&quot; separator.
  I tried to concatenate them with stream :</p>
  <pre><code>objList.stream().collect(Collectors.joining(&quot;.&quot;));
  </code></pre>
  <p>But I can't figure it out how to concat only parameters from objects.</p>
  <p>In this case the result should be &quot;val1.val2&quot;</p>