BSIDL 3.1 supports defining a response as both a "response" and a "simpleResponse". This mangler simply converts "response" elements to "simpleResponse" elements so that we can continue to work with the same old ftls. It throws an IllegalArgumentException if the idd specifies both - this is allowed by the xsd, but is complete nonsense.
If at some point support for "simpleResponse" is dropped from BSIDL then this mangler can be removed and the ftls updated to check for "response" instead.