The generated Java classes corresponding to valuetype IDL types implement this interface.

  The generated Java classes corresponding to valuetype IDL types
implement this interface. In other words, the Java mapping of
valuetype objects implement the ValueBase interface. The generated
Java class for valuetype's shall provide an implementation of the
ValueBase interface for the corresponding value type.
For value types that are streamable (i.e. non-custom),
the generated Java class shall also provide an implementation
for the org.omg.CORBA.portable.Streamable interface.
(CORBA::ValueBase is mapped to java.io.Serializable.)