I’ve just come across what I believe is a weird behaviour in Jackson XML (de)serialization.

The character uFFFF is accepted when serializing but leads to an error when deserialized.

XmlMapper xml = new XmlMapper();

String xmlString = xml.writeValueAsString("Some valid string but containing the uFFFF character");
System.out.println(xmlString);
// <String>Some valid string but containing the &#xffff; character</String>

String deser = xml.readValue(xmlString, String.class);
System.out.println(deser);
// java.lang.RuntimeException: com.fasterxml.jackson.core.JsonParseException: Illegal character entity: expansion character (code 0xffff
// at [row,col {unknown-source}]: [1,53]
// at [Source: (StringReader); line: 1, column: 54]

What is the proper way of handling this? How to tell Jackson to not write this character if it doesn’t support reading it back?

(Jackson version: 2.17.1)