code: protected Image convertToImage(Object imageDescription) {
  		if (imageDescription instanceof Image) {
  			return (Image) imageDescription;
  		} else if (imageDescription instanceof ImageDescriptor) {
  			return this.imageHelper.getImage((ImageDescriptor) imageDescription);
  		} else if (imageDescription instanceof String) {
  			return this.imageHelper.getImage((String) imageDescription);
  		}
  		return null;
  	}
docs: Replies the image that corresponds to the given object.
  
  @param imageDescription
  a {@link String}, an {@link ImageDescriptor} or an {@link Image}
  @return the {@link Image} associated with the description or <code>null</code>