SEC-2870: Add Spring Data Documentation

docs/manual/src/docs/asciidoc/index.adoc

@@ -6201,6 +6201,52 @@ public class CsrfController {
 It is important to keep the `CsrfToken` a secret from other domains.
 This means if you are using https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS[Cross Origin Sharing (CORS)], you should **NOT** expose the `CsrfToken` to any external domains.
 
+[[data]]
+= Spring Data Integration
+
+Spring Security provides Spring Data integration that allows referring to the current user within your queries.
+It is not only useful but necessary to include the user in the queries to support paged results since filtering the results afterwards would not scale.
+
+[[data-configuration]]
+== Spring Data & Spring Security Configuration
+
+To use this support, provide a bean of type `SecurityEvaluationContextExtension`.
+In Java Configuration, this would look like:
+
+[source,java]
+----
+@Bean
+public SecurityEvaluationContextExtension securityEvaluationContextExtension() {
+    return new SecurityEvaluationContextExtension();
+}
+----
+
+In XML Configuration, this would look like:
+
+[source,xml]
+----
+<bean class="org.springframework.security.data.repository.query.SecurityEvaluationContextExtension"/>
+----
+
+[[data-query]]
+== Security Expressions within @Query
+
+Now Spring Security can be used within your queries.
+For example:
+
+[source,java]
+----
+@Repository
+public interface MessageRepository extends PagingAndSortingRepository<Message,Long> {
+    @Query("select m from Message m where m.to.id = ?#{ principal?.id }")
+    Page<Message> findInbox(Pageable pageable);
+}
+----
+
+This checks to see if the `Authentication.getPrincipal().getId()` is equal to the recipient of the `Message`.
+Note that this example assumes you have customized the principal to be an Object that has an id property.
+By exposing the `SecurityEvaluationContextExtension` bean, all of the <<common-expressions,Common Security Expressions>> are available within the Query.
+
 = Appendix
 
 [[appendix-schema]]