Some PDF have an empty string as CreationDate & ModDate in the Information Dictionary.
According to the PDF specification, this two element are optional.
My first fix was to test the null & the empty string in the toCalendar(String, String) method and I return null if one of the both condition is verified.
But according to a test case(TestDateUtil) a NullPointer is expected on null value of text. Can you explain why this behaviour has been adopted?
To fixe this unexpected exception in my execution path, I have added a test on the empty string in the deprecated method toCalendar(String). (Patch in attachment)
I'm waiting your comment before commit this patch (or change it by my first implementation)