docs: public JavacFiler getJavacFiler(Object filer) {
  		if (filer instanceof JavacFiler) return (JavacFiler) filer;
  		
  		// try to find a "delegate" field in the object, and use this to check for a JavacFiler
  		for (Class<?> filerClass = filer.getClass(); filerClass != null; filerClass = filerClass.getSuperclass()) {
  			try {
  				return getJavacFiler(tryGetDelegateField(filerClass, filer));
  			} catch (final Exception e) {
  				// delegate field was not found, try on superclass
  			}
  		}
  		
  		processingEnv.getMessager().printMessage(Kind.WARNING,
  			"Can't get a JavacFiler from " + filer.getClass().getName() + ". Lombok won't work.");
  		return null;
  	}