xs:keyref not working

Take an XSD like this one here:

<xs:schema attributeFormDefault='unqualified' elementFormDefault='qualified' xmlns:xs='http://www.w3.org/2001/XMLSchema'>
  <xs:complexType name='source'>
    <xs:attribute name='name' type='xs:string' use='required'/>
  </xs:complexType>

  <xs:complexType name='target'>
    <xs:choice minOccurs='0' maxOccurs='unbounded'>
      <xs:element name='reference' type='xs:string'/>
    </xs:choice>
  </xs:complexType>

  <xs:complexType name='root'>
    <xs:choice minOccurs='0' maxOccurs='unbounded'>
      <xs:element name='source' type='source'/>
      <xs:element name='target' type='target'/>
    </xs:choice>
  </xs:complexType>

  <xs:element name='root' type='root'>
    <xs:unique name='unique.source.name'>
      <xs:selector xpath='source'/>
      <xs:field xpath='@name'/>
    </xs:unique>
    <xs:keyref name='keyref.target.reference' refer='unique.source.name'>
      <xs:selector xpath='target'/>
      <xs:field xpath='reference'/>
    </xs:keyref>
  </xs:element>
</xs:schema>

with an XML like this:

<root>
  <source name='test1'/>
  <source name='test1'/>
  <target>
    <reference>test2</reference>
  </target>
</root>

The extension will recognize that "test1" is duplicate (xs:unique works) but it will neither recognize that "test2" does not refer to a known name nor does it propose names on completion inside the "reference" tag at all.

Reproduce the issue with the supplied XSD and XML, then trace how the extension handles xs:unique, xs:keyref validation, and completion inside reference elements. Done means the invalid test2 reference is reported and completion proposes the relevant source names.