The elements sp, pc are optional but the struct Address in module contact makes them compulsory.
Here is the schema definition from RFC 5733, page 31
<complexType name="addrType">
<sequence>
<element name="street" type="contact:optPostalLineType"
minOccurs="0" maxOccurs="3"/>
<element name="city" type="contact:postalLineType"/>
<element name="sp" type="contact:optPostalLineType"
minOccurs="0"/>
<element name="pc" type="contact:pcType"
minOccurs="0"/>
<element name="cc" type="contact:ccType"/>
</sequence>
</complexType>
Should I fix this and submit PR?