The ValueFactory interface is the native mapping for the IDL
type CORBA::ValueFactory. The read_value() method is called by
the ORB runtime while in the process of unmarshaling a value type.
A user shall implement this method as part of implementing a type
specific value factory. In the implementation, the user shall call
is.read_value(java.io.Serializable) with a uninitialized valuetype
to use for unmarshaling. The value returned by the stream is
the same value passed in, with all the data unmarshaled.