title: Java ternary operator (?:) doesn't work; second or third operand return boolean
body: <p>Can someone tell me why this use of the ternary operator is incorrect? Operands 2 and 3 return a boolean.</p>
  
  <pre><code>public class Something {
  ...
  private static final double REFERENCE_FRAME_MID_X = 0;
  private static final double REFERENCE_FRAME_MID_Y = 0;
  
  private boolean findInsideOrOutsideGeneralEllipse(Point2D destCirclePos) {
      List&lt;Boolean&gt; returnValue = new ArrayList&lt;&gt;();
      Point2D referenceFrameCenter = new Point2D.Double(REFERENCE_FRAME_MID_X, REFERENCE_FRAME_MID_Y);
      Ellipse2D insideAreaEllipse2D = getEllipse2D(referenceFrameCenter.getX(), referenceFrameCenter.getY(),
                                                      destCirclePos.distance(referenceFrameCenter));
  
      // doesn't work
      insideAreaEllipse2D.contains(destCirclePos) ? returnValue.add(true) : returnValue.add(false);
  
      // works
      if (insideAreaEllipse2D.contains(destCirclePos)) {
          returnValue.add(true);
      } else {
          returnValue.add(false);
      }
  }
  ...
  }
  </code></pre>