Expand test wrt [databind#5860], improve XmlMapper support for it#843

cowtowncoder merged 2 commits into3.xFasterXML/jackson-dataformat-xml:3.xfrom

tatu-claude/3.2/databind-5860-generator-initializerFasterXML/jackson-dataformat-xml:tatu-claude/3.2/databind-5860-generator-initializerCopy head branch name to clipboard