title: Angular RouterLink queryParamsHandling for optional params
body: <p>Is there a clean way to merge the current optional queryParams with an additional optional queryParam on a link in the template?</p>
  
  <p>Current url: <code>/search;brand=Trek</code></p>
  
  <p>Desired goto link: <code>/search;brand=Trek;start=1</code> (startCount will be incremented)</p>
  
  <p>I know Angular supports the ability to merge <strong>normal</strong> queryParams (<a href="https://angular.io/docs/ts/latest/api/router/index/RouterLink-directive.html" rel="nofollow noreferrer">https://angular.io/docs/ts/latest/api/router/index/RouterLink-directive.html</a>), but I don't think it works with <strong>optional</strong> queryParams.</p>
  
  <p>That's why this doesn't work:</p>
  
  <pre><code>&lt;a class="nav-btn"
     queryParamsHandling="merge"
     [routerLink]="[ { start: startCount+1 } ]"&gt;
      Next Page
  &lt;/a&gt;
  </code></pre>
  
  <p>Any suggestions?</p>