Java Development Tools

Hi,

I am using 11g.

I have a form wherein somefields are not manadatory and it can be submitted null, how can I achieve this?
Here is the code I am using. I tried it with and without value="" . Didn't work.

Error I get on submit:

java.lang.NullPointerException
ADF_FACES-60097:For more information, please see the server's error log for an entry beginning with: ADF_FACES-60096:Server Exception during PPR, #1

JSP:

<af:inputText label="Order Source" id="it35"
                                        value=""
                                        binding="#{pageFlowScope.invoiceTableManagedBean.orderSource}"/> 

Bean:

     private RichInputText orderSource;

    public void setOrderSource(RichInputText orderSource) {
        this.orderSource = orderSource;
        //this.orderSource = orderSource;
    }

    public RichInputText getOrderSource() {
        return orderSource;
    }