Hi martin, As well as i had implement the Serializable in Anonymous inner class (DefaultObjectAutoCompleteBuilder.class) of HomePage now the Exception didn't come but one warning message came like this.
WARN - WebSession - Component-targetted feedback message was left unrendered. This could be because you are missing a FeedbackPanel on the page. Message: [FeedbackMessage message = "'S' is not a valid Serializable.", reporter = hiddenId, level = ERROR] and the form doesn't submit. -Vignesh Palanisamy