This bug is slightly similar to #358125

Given this valid XSD:

<?xml version="1.0" encoding="UTF-8"?>                                                                                                                                                 

<xs:schema                                                                                                                                                                             
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  xmlns:example="http://example.com"
  targetNamespace="http://example.com"
  elementFormDefault="qualified"
  >

  <xs:complexType name="address">
    <xs:all>
      <xs:element name="country" type="xs:string"></xs:element>
      <xs:element name="state" type="xs:string"></xs:element>
      <xs:element name="city" type="xs:string"></xs:element>
    </xs:all>
  </xs:complexType>

  <xs:element name="person">
    <xs:complexType>
      <xs:all>
        <xs:element name="name" type="xs:string"></xs:element>
        <xs:element name="address" type="example:address" nillable="true"></xs:element>
      </xs:all>
    </xs:complexType>
  </xs:element>

</xs:schema>


and this valid document:

<?xml version="1.0" encoding="UTF-8"?>                                                                                                                                                 

<person
  xmlns="http://example.com"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  >
  <name>Bob</name>
  <address xsi:nil="true" />
</person>

Validation fails:
$ xmllint -schema person.xsd person.xml 
<?xml version="1.0" encoding="UTF-8"?>
<person xmlns="http://example.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <name>Bob</name>
  <address xsi:nil="true"/>
</person>
person.xml:8: element address: Schemas validity error : Element '{http://example.com}address': Missing child element(s). Expected is one of ( {http://example.com}country, {http://example.com}state, {http://example.com}city ).
person.xml fails to validate

It seems it insists on validating the innards of "address" even though it's specified as nil, and its definition in the schema allows it to be nil.

Through experimentation I've found two variations to the above that makes validation succeed, though logically undesirable on my end:

1. set minOccurs="0" to country/state/city in the schema
OR
2. Change the complexType definition from :sequence to :all


It seems the similar bug I mentioned (#358125) was only centered around xs:sequence, and this bug is around xs:all