Java - Castor XML mapping : how to concatenate two Java field values into one XML attribute value and vice versa

Question

Consider the following period : 2017-11-03 to 2017-11-06

• The XML has one element : TimePeriodCovered: v="2017-11-03T00:00Z/2017-11-06T00:00Z" which is a concatenation of two dates ;
• The Java object maps this field with two attributes (Date) : startPeriod & endPeriod

.java

public class foo implements Serializable {

    private Date startPeriod;

    private Date endPeriod;

    ...
}

.xsd

<xs:element name="container" >
    <xs:complexType>
        <xs:sequence>
            <xs:element name="foo" type="fooType" />
            ...
        </xs:sequence>
    </xs:complexType>
</xs:element>


<xs:complexType name="fooType">
    <xs:sequence>
        <xs:element name="TimePeriodCovered" minOccurs="0" type="PeriodType" />
        ...
    </xs:sequence>
</xs:complexType>

<xs:complexType name="PeriodType">
    <xs:attribute name="v" use="required">
        <xs:simpleType>
            <xs:restriction base="xs:string">
                <xs:pattern value="[1-2][0-9][0-9][0-9]-[0-1][0-9]-[0-3][0-9]T[0-2][0-9]:[0-6][0-9]Z?/[1-2][0-9][0-9][0-9]-[0-1][0-9]-[0-3][0-9]T[0-2][0-9]:[0-6][0-9]Z?" />
            </xs:restriction>
        </xs:simpleType>
    </xs:attribute>
</xs:complexType>

mapping.xml

I have absolutely no idea. What should it be ?