code: public static ConversionService getSharedInstance() {
  		ApplicationConversionService sharedInstance = ApplicationConversionService.sharedInstance;
  		if (sharedInstance == null) {
  			synchronized (ApplicationConversionService.class) {
  				sharedInstance = ApplicationConversionService.sharedInstance;
  				if (sharedInstance == null) {
  					sharedInstance = new ApplicationConversionService();
  					ApplicationConversionService.sharedInstance = sharedInstance;
  				}
  			}
  		}
  		return sharedInstance;
  	}
docs: Return a shared default application {@code ConversionService} instance, lazily
  building it once needed.
  <p>
  Note: This method actually returns an {@link ApplicationConversionService}
  instance. However, the {@code ConversionService} signature has been preserved for
  binary compatibility.
  @return the shared {@code ApplicationConversionService} instance (never
  {@code null})