I have come across two bugs for which I provide basic fixes here.

1. If an element with a substitutionGroup did not have an explicit type, an IllegalStateException was thrown because of schemaType == null and !element.isAbstract(). Example:

<xs:element name="any" type="SimpleLiteral" abstract="true"/>
<xs:element name="title" substitutionGroup="any"/>

Here, the exception occurred when walking through the title element. My fix now considers the type of the substitutionGroup element if no explicit is given.

2. A ClassCastException happened when a particle of type xs:all occurred in an xs:extension, e.g.

<xs:complexContent>
	<xs:extension base="baseType">
		<xs:all> ...

I added a simple check and add the xs:all items to the constructed sequence separately.