DATACASS-784 - Add support for reactive auditing.

We now support reactive auditing by providing the EnableReactiveCassandraAuditing annotation. Previously, EnableCassandraAuditing no longer registers ReactiveAuditingEntityCallback for date-only auditing, the callback is now only registered when using EnableReactiveCassandraAuditing.

src/main/asciidoc/new-features.adoc

@@ -3,6 +3,11 @@
 
 This chapter summarizes changes and new features for each release.
 
+[[new-features.3-1-0]]
+== What's new in Spring Data for Apache Cassandra 3.1
+
+* <<cassandra.auditing,Reactive auditing>> enabled through `@EnableReactiveCassandraAuditing`. `@EnableCassandraAuditing` no longer registers `ReactiveAuditingEntityCallback`.
+
 [[new-features.3-0-0]]
 == What's new in Spring Data for Apache Cassandra 3.0
 

src/main/asciidoc/reference/cassandra-auditing.adoc

@@ -31,3 +31,23 @@ class Config {
 
 If you expose a bean of type `AuditorAware` to the `ApplicationContext`, the auditing infrastructure picks it up automatically and uses it to determine the current user to be set on domain types.
 If you have multiple implementations registered in the `ApplicationContext`, you can select the one to be used by explicitly setting the `auditorAwareRef` attribute of `@EnableCassandraAuditing`.
+
+To enable auditing, leveraging a reactive programming model, use the `@EnableReactiveCassandraAuditing` annotation. +
+If you expose a bean of type `ReactiveAuditorAware` to the `ApplicationContext`, the auditing infrastructure picks it up automatically and uses it to determine the current user to be set on domain types.
+If you have multiple implementations registered in the `ApplicationContext`, you can select the one to be used by explicitly setting the `auditorAwareRef` attribute of `@EnableReactiveCassandraAuditing`.
+
+.Activating reactive auditing using JavaConfig
+====
+[source,java]
+----
+@Configuration
+@EnableReactiveCassandraAuditing
+class Config {
+
+  @Bean
+  public ReactiveAuditorAware<AuditableUser> myAuditorProvider() {
+      return new AuditorAwareImpl();
+  }
+}
+----
+====