How to disable type conversion error in Struts 2

I have a text field in my form for start date. The data type in my action for that field is date. I have custom validation for that date field in my validate method. When ever i have an invalid date keyed in that field, i'm getting 2 errors.

1 from the Struts 2 type conversion interceptor (i guess) "Invalid field value for field startDate".
2 from my custom validation from the validate method "Start Date required". The reason why i'm getting this is because i believe Struts 2 automatically clears the data if it is invalid and when the code reaches the validate method, the field has no value.

I would like to disable the type conversion error checks so that only one message is shown to the user.

Any help is appreciated.