wildfly: XML validation manipulation due to incomplete application of use-grammar-pool-only in xercesImpl

A flaw was found in Wildfly's implementation of Xerces, specifically in the way the XMLSchemaValidator class in the JAXP component of Wildfly enforced the "use-grammar-pool-only" feature. This flaw allows a specially-crafted XML file to manipulate the validation process in certain cases. This iss...