The following comes from the BIAS spec: biasprofile-v1.0-csprd02

Additionally, the WSDL exposed by an implementation shall not contain instances of xsd:any, xsd:anyType, or xsd:anyAttribute; these instances must be replaced with explicit schema contents. An example is the XML complex type, InformationType, which has xsd:any as its only child. This type is used to represent implementation-specific input data and return data. The children of InformationType must be replaced with explicit content. Doing so removes the ability to transmit unexpected or arbitrary data. Also, it provides a clear definition of information that a client needs to provide to the server,or expect to receive,to optimally perform an operation.

This is also an issue for the SOAP service and its use of any.

In practice with JAXB the xs:any element doesn't work well. The returned type is

com.sun.org.apache.xerces.internal.dom.ElementNSImpl

Tried changing the XRD schema to use substitution groups - didn't work.