title: State of Binder#hasChanges() after user takes back changes
body: <p>For an binder without a bound bean, the <code>hasChange()</code> method returns <code>true</code> as soon as a bound field is changed. But it's still <code>true</code> after the change gets reverted. So I'm looking for something like <code>isEqualToInitialState()</code>, in order to enable the save button for real changes only.</p>
  <p>Is there a best practice for my intention? I also do not see a method like <code>hasChangesComparedTo(Bean bean)</code>.</p>