For JAXB we could use Inline Customization to adjust schema compiler in some way. This could be done via Schema Binding Declarations (<jxb:schemaBindings/>).
Any way to make other XML tags (e.g. ActualType, EnumerationValue in example below) work with standard XJC compiler to affect generated classes?
<xs:simpleType name="SomeType">
<xs:annotation>
<xs:appinfo>
<ActualType Name="unsignedInt" />
</xs:appinfo>
</xs:annotation>
<xs:restriction base="xs:string">
<xs:enumeration value="PredefinedEnumValue">
<xs:annotation>
<xs:appinfo>
<EnumerationValue>10000</EnumerationValue>
</xs:appinfo>
</xs:annotation>
</xs:enumeration>
</xs:restriction>
</xs:simpleType>