I had a NullPointerException reported to Byte Buddy: https://github.com/raphw/byte-buddy/issues/625

The reason is that two visitors are only created if a security manager is set during the creation of: https://github.com/hibernate/hibernate-orm/blob/master/hibernate-core/src/main/java/org/hibernate/bytecode/internal/bytebuddy/ByteBuddyState.java#L84

If the security manager is set later, both visitors are null such that the exception occurs.