Spring Session docs PDF do not display sample code

[eleftherias]

This is the case for version 2.3.0.RC1.
Instead of the sample code, the following error message is shown:

Unresolved directive in guides/java-redis.adoc - include::{samples-dir}springsession-sample-javaconfig-redis/src/main/java/sample/Initializer.java[tags=class]