TestRig exports invalid SVG

[1] Damn! Github made it look like my description was not entered as I added to the comment rather than uncommenting it.

• I have reproduced my issue using the latest version of ANTLR
• I have asked at stackoverflow
  Obviously a fault
• Responses from the above seem to indicate that my issue could be an ANTLR bug
  N/A
• I have done a search of the existing issues to make sure I'm not sending in a duplicate

Please include the following information:

• target information (Java, C++ ...)
  Java
  I am targeting .net, Javascript and Python but using the test rig which parses to Java.
• smallest possible grammar and code that reproduces the behavior [[behaviour]]
  Smaller example does not reproduce fault.
• description of the expected behavior [2] [[behaviour]] and actual behavior [[behaviour]]
  Pointers to suspicious code regions are also very welcome.

Run antlr on the attached grammar.
Xenon.g4.zip

antlr4 Xenon.g4

Complete the parser

javac *.java

Run the testrig

grun Xenon xenon -gui config.xenon

Export to SVG
The .svg is attached

Open the .svg in say Microsoft Edge.

This page contains the following errors:
error on line 196 at column 6: xmlParseEntityRef: no name
Below is a rendering of the page up to the first error.

Reproduce the problem with the attached Xenon.g4 grammar using the listed antlr4, javac, and grun commands, then validate the generated SVG in an XML parser. Inspect the exported SVG around line 196 and compare it with the TestRig output to identify what makes the document invalid; done means the export opens without XML errors.