Cannot get signature hash string to work correctly

[rwilson3297]

I can generate the hash string and get the API call to work through Postman using the API Live Console page and allowing it to generate the hash. However I can never get the hash to work when generated through Java Code. It never generates the same one twice because of the datetime, but none of them work when I input in Postman. I'm also referencing the API guide, but I'm just not getting something right when creating the signature hash. Any ideas on things I can check?