Set default value for date field in entity

[xxshutong]

Dear friends,
I want to set a date field in entity to current time. I use service as bellow:

<service name="createInput" default-entity-name="InventoryInput" 
engine="entity-auto" invoke="create" auth="true">
        <description>Create a new input record</description>
        <!--<permission-service service-name="exampleGenericPermission" 
main-action="CREATE"/>-->
        <auto-attributes include="pk" mode="OUT" optional="false"/>
        <auto-attributes include="nonpk" mode="IN" optional="true"/>
        <override name="machine_no" optional="false"/>
        <override name="product_id" optional="false"/>
        <override name="batch_no_id" optional="false"/>
        <override name="inputDate" default-value="${bsh: 
org.ofbiz.base.util.UtilDateTime.nowTimestamp()}"/>
   </service>

But the bold part can't work correctly, any suggestions?

Thanks,
Leon.Zhou