It's hard to answer this question, because we don't know what your Order and WestOrder classes look like, and what the DETAILS string contains. A String is a totally different kind of object than an Order or a WestOrder. It sounds like this:
Trying to fit a square peg in a round hole
There is no generic way to pass a String to a method that takes a different kind of object. Does the DETAILS string contain information on an order? What does it look like? Maybe you need to parse the string, make an Order object and set the fields of that object using information found in the string?