code: public Boolean isOverlayInstalled(JComponent targetComponent, JComponent overlay) {
  
          Assert.notNull(targetComponent, JideOverlayService.TARGET_COMPONENT_PARAM);
          Assert.notNull(overlay, JideOverlayService.OVERLAY);
  
          final DefaultOverlayable overlayable = this.findOverlayable(targetComponent);
  
          return this.isOverlayInstalled(overlayable, overlay);
      }
docs: {@inheritDoc}