[XERCESJ-1652] xsi:type in element of union datatype makes validation fail. Example from XML Schema spec fails.

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.10.0
• Component/s: JAXP (javax.xml.validation)
• Environment: Java 7 x64, Linux Ubuntu 14.04 x64
• Assignee: Unassigned
• Reporter: Nikolay Pakulin
• Created: 24/Nov/14 18:44
• Updated: 30/Nov/14 08:14

Description

XML Schema Part 2: Datatypes Second Edition, section 2.5.1.3 Union datatypes (http://www.w3.org/TR/xmlschema-2/#union-datatypes) specifies that xsi:type attribute may be used to tell the exact variant of a union type used in the instance element.
There is an example on how to use xsi:type attribute. That example does not pass in xerces-j:
cvc-elt.4.3: Type 'xsd:string' is not validly derived from the type definition, 'null', of element 'size'.

The sample XSD and instance document are available from https://www.dropbox.com/s/th1v2ts88cxad8x/union_datatype_xsi_type.zip?dl=0