For any other locale than English, proper messages are not shown for exception.
I tried to throw an exception using French locale, the printStackTrace is as follows:
org.xml.sax.SAXParseException: org.apache.crimson.parser/P-014 mkm
        at org.apache.crimson.parser.Parser2.fatal(Parser2.java:3035)
        at org.apache.crimson.parser.Parser2.fatal(Parser2.java:3029)
        at
org.apache.crimson.parser.Parser2.expandEntityInContent(Parser2.java:2389)
        at
org.apache.crimson.parser.Parser2.maybeReferenceInContent(Parser2.java:2298)
        at org.apache.crimson.parser.Parser2.content(Parser2.java:1754)
        at org.apache.crimson.parser.Parser2.maybeElement(Parser2.java:1468)
        at org.apache.crimson.parser.Parser2.content(Parser2.java:1700)
        at org.apache.crimson.parser.Parser2.maybeElement(Parser2.java:1468)
        at org.apache.crimson.parser.Parser2.parseInternal(Parser2.java:499)
        at org.apache.crimson.parser.Parser2.parse(Parser2.java:304)
        at org.apache.crimson.parser.XMLReaderImpl.parse(XMLReaderImpl.java:433)
        at org.xml.sax.helpers.XMLReaderAdapter.parse(XMLReaderAdapter.java:223)
        at javax.xml.parsers.SAXParser.parse(SAXParser.java:310)
        at javax.xml.parsers.SAXParser.parse(SAXParser.java:101)
        at SAX01.main(SAX01.java:33)
where as the expected message for the Exception with US-English as Locale is as follows :
org.xml.sax.SAXParseException: Reference to undefined entity "&mkm;".