title: Register a reactor to trigger on a custom parameter with the API?
body: <p>I have a reactor that has to react to changes done upon a custom parameter. When you register the reactor, you specify the type of change it reacts to.</p>
  
  <pre><code>UpdaterRegistry.AddTrigger(updaterId, RevitFilters.StructuralElementsFilter, Element.GetChangeTypeAny());
  </code></pre>
  
  <p>The following are the changetypes allowed by the API:</p>
  
  <pre><code>public static ChangeType GetChangeTypeAny();
  public static ChangeType GetChangeTypeElementAddition();
  public static ChangeType GetChangeTypeElementDeletion();
  public static ChangeType GetChangeTypeGeometry();
  public static ChangeType GetChangeTypeParameter(ElementId parameterId);
  public static ChangeType GetChangeTypeParameter(Parameter param);
  </code></pre>
  
  <p>I'd like to use <code>GetChangeTypeParameter(Parameter param)</code> or <code>ChangeType GetChangeTypeParameter(ElementId parameterId)</code> but I didn't find a proper way so far.</p>