Help with CNFE with Afterburner creating property accessor class

Using jackson 2.11.3/Java 1.8 - normal classpath web class loader

I'm seeing CNFE in my logs with afterburner, trying to build a class for

javax.ws.rs.BadRequestException$Access4
JacksonSerializer76314150'

Which i take it it's trying to build a class to access properties of BadRequestException.

BadRequestException comes out of javax.ws.rs-api.jar version 2.1.1

Looking at that class, i don't see any obviously tricky properties to foul things up. Any ideas what to look for?

com.fasterxml.jackson.databind.JsonMappingException: Failed to load class 'javax.ws.rs.BadRequestException$Access4
JacksonSerializer76314150': com.fasterxml.jackson.module.afterburner.ser.BeanPropertyAccessor
at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:295) ~[jackson-databi
nd.jar:2.11.3]
#######################################
Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.module.afterburner.ser.BeanPropertyAccessor
at java.lang.ClassLoader.findClass(ClassLoader.java:523) ~[?:1.8.0_231]
at java.lang.ClassLoader.loadClass(ClassLoader.java:418) ~[?:1.8.0_231]
at java.lang.ClassLoader.loadClass(ClassLoader.java:351) ~[?:1.8.0_231]
at java.lang.ClassLoader.defineClass1(Native Method) ~[?:1.8.0_231]
at java.lang.ClassLoader.defineClass(ClassLoader.java:756) ~[?:1.8.0_231]
at java.lang.ClassLoader.defineClass(ClassLoader.java:635) ~[?:1.8.0_231]
at com.fasterxml.jackson.module.afterburner.util.MyClassLoader.loadAndResolve(MyClassLoader.java:90) ~[jack
son-module-afterburner.jar:2.11.3]