The schema/infinispan-config-4.2.xsd file included in the released JAR has the following header:

<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" version="1.0" targetNamespace="urn:infinispan:config:5.0" xmlns:tns="urn:infinispan:config:5.0" xmlns:xs="http://www.w3.org/2001/XMLSchema">

Where instead it should refer to 4.2.