title: How to solve exception with inbound-channel-adapter poller?
body: <p>Сould not find an answer.<br>
  Spring version 5.0.6.<br>
  My config:   </p>
  
  <pre><code>&lt;int:channel id="data"/&gt;
  
  &lt;int:inbound-channel-adapter 
      id="dataAdapter"                                                                    
      channel="data"                                    
      auto-startup="false"
      ref="dataGetter"
      method="myMessageSource"&gt;
      &lt;int:poller max-messages-per-poll="10"/&gt;
  &lt;/int:inbound-channel-adapter&gt;
  &lt;beans:bean
      class="org.endpoints.DataGetter"
      id="dataGetter"/&gt;
  </code></pre>
  
  <p></p>
  
  <p>Throw exception:  </p>
  
  <pre><code>Configuration problem: A &lt;poller&gt; must have one and only one trigger configuration.
  </code></pre>
  
  <p>If no poller: </p>
  
  <pre><code>No poller has been defined for channel-adapter 'dataAdapter', and no default poller is available within the context.
  </code></pre>
  
  <p>How to properly setup the poller?</p>