XML : How do I correct XSD for JAXB generator?

I prepared complexType, an enum with two attributes:

  <xsd:complexType name="Action">      <xsd:simpleContent>          <xsd:restriction base="xsd:string">              <xsd:enumeration value="A"/>              <xsd:enumeration value="B"/>              <xsd:enumeration value="C"/>          </xsd:restriction>      </xsd:simpleContent>      <xsd:attribute name="attrA" type="xsd:string" />      <xsd:attribute name="attrB" type="xsd:string" />  </xsd:complexType>    

The problem is, JAXB prevents me from creating Java classes for that code, I get the following error:

  When <simpleContent> is used, the base type must be a complexType whose content  type is simple, or, only if restriction is specified, a complex type with mixed  content and emptiable particle, or, only if extension is specified, a simple type.  'string' satisfies none of these conditions.    

Online validator showed me my code is corrent one. How do I change this to make xjc convert my schema definition?