Refine Querydsl documentation.

Closes #538

pom.xml

@@ -75,7 +75,7 @@
 
 		<dependency>
 			<groupId>com.querydsl</groupId>
-			<artifactId>querydsl-mongodb</artifactId>
+			<artifactId>querydsl-core</artifactId>
 			<version>${querydsl}</version>
 			<optional>true</optional>
 		</dependency>

src/main/antora/modules/ROOT/nav.adoc

@@ -19,7 +19,6 @@
 ** xref:ldap/usage.adoc[]
 ** xref:ldap/query-methods.adoc[]
 ** xref:ldap/value-expressions.adoc[]
-** xref:ldap/querydsl.adoc[]
 ** xref:ldap/cdi-integration.adoc[]
 
 * xref:attachment$api/java/index.html[Javadoc,role=link-external,window=_blank]

src/main/antora/modules/ROOT/pages/repositories/core-extensions.adoc

@@ -1 +1,175 @@
-include::{commons}@data-commons::page$repositories/core-extensions.adoc[]
+[[core.extensions]]
+= Spring Data Extensions
+
+This section documents a set of Spring Data extensions that enable Spring Data usage in a variety of contexts.
+Currently, most of the integration is targeted towards Spring MVC.
+
+include::{commons}@data-commons::page$repositories/core-extensions-querydsl.adoc[leveloffset=1]
+
+[[ldap.repositories.queries.type-safe]]
+=== Type-safe Query Methods with Querydsl
+
+LDAP repository counterpart integrates with the http://www.querydsl.com/[Querydsl] project, which provides a way to perform type-safe queries.
+
+[quote,Querydsl Team]
+Instead of writing queries as inline strings or externalizing them into XML files they are constructed via a fluent API.
+
+It provides the following features:
+
+* Code completion in the IDE (all properties, methods, and operations can be expanded in your favorite Java IDE).
+* Almost no syntactically invalid queries allowed (type-safe on all levels).
+* Domain types and properties can be referenced safely -- no strings involved!
+* Adapts better to refactoring changes in domain types.
+* Incremental query definition is easier.
+
+See the http://www.querydsl.com/static/querydsl/latest/reference/html/[Querydsl documentation] for how to bootstrap your environment for APT-based code generation using Maven or Ant.
+
+Querydsl lets you write queries such as the following:
+
+====
+[source,java,indent=0,subs="verbatim,quotes",role="primary"]
+----
+QPerson person = QPerson.person;
+List<Person> result = repository.findAll(person.address.zipCode.eq("C0123"));
+
+Page<Person> page = repository.findAll(person.lastname.contains("a"),
+                                       PageRequest.of(0, 2, Direction.ASC, "lastname"));
+----
+====
+
+`QPerson` is a class that is generated by the Java annotation processor.
+See xref:#ldap.repositories.queries.type-safe.apt[Setting up Annotation Processing] for how to set up Annotation Processing with your Build System.
+It is a `Predicate` that lets you write type-safe queries.
+Notice that there are no strings in the query other than the `C0123` value.
+
+You can use the generated `Predicate` class by using the `QuerydslPredicateExecutor` interface, which the following listing shows:
+
+====
+[source,java,indent=0,subs="verbatim,quotes",role="primary"]
+----
+public interface QuerydslPredicateExecutor<T> {
+
+    Optional<T> findOne(Predicate predicate);
+
+    List<T> findAll(Predicate predicate);
+
+    List<T> findAll(Predicate predicate, Sort sort);
+
+    List<T> findAll(Predicate predicate, OrderSpecifier<?>... orders);
+
+    Page<T> findAll(Predicate predicate, Pageable pageable);
+
+    List<T> findAll(OrderSpecifier<?>... orders);
+
+    long count(Predicate predicate);
+
+    boolean exists(Predicate predicate);
+
+    <S extends T, R> R findBy(Predicate predicate, Function<FluentQuery.FetchableFluentQuery<S>, R> queryFunction);
+}
+----
+====
+
+To use this in your repository implementation, add it to the list of repository interfaces from which your interface inherits, as the following example shows:
+
+====
+[source,java,indent=0,subs="verbatim,quotes",role="primary"]
+----
+interface PersonRepository extends LdapRepository<Person>, QuerydslPredicateExecutor<Person> {
+
+    // additional query methods go here
+}
+----
+====
+
+[[ldap.repositories.queries.type-safe.apt]]
+=== Setting up Annotation Processing
+
+To use Querydsl with Spring Data LDAP, you need to set up annotation processing in your build system that generates the `Q` classes.
+While you could write the `Q` classes by hand, it is recommended to use the Querydsl annotation processor to generate them for you to keep your `Q` classes in sync with your domain model.
+
+Spring Data LDAP ships with an annotation processor javadoc:org.springframework.data.ldap.repository.support.LdapAnnotationProcessor[] that isn't registered by default.
+Typically, annotation processors are registered through Java's service loader via `META-INF/services/javax.annotation.processing.Processor` that also activates these once you have them on the class path.
+Most Spring Data users do not use Querydsl, so it does not make sense to require additional mandatory dependencies for projects that would not benefit from Querydsl.
+Hence, you need to activate annotation processing in your build system.
+
+The following example shows how to set up annotation processing by mentioning dependencies and compiler config changes in Maven and Gradle:
+
+[tabs]
+======
+Maven::
++
+[source,xml,indent=0,subs="verbatim,quotes",role="primary"]
+----
+<dependencies>
+    <dependency>
+        <groupId>org.springframework.data</groupId>
+        <artifactId>spring-data-ldap</artifactId>
+    </dependency>
+
+    <dependency>
+        <groupId>com.querydsl</groupId>
+        <artifactId>querydsl-core</artifactId>
+        <version>${querydslVersion}</version>
+        <classifier>jakarta</classifier>
+    </dependency>
+
+    <dependency>
+        <groupId>com.querydsl</groupId>
+        <artifactId>querydsl-apt</artifactId>
+        <version>${querydslVersion}</version>
+        <classifier>jakarta</classifier>
+        <scope>provided</scope>
+    </dependency>
+</dependencies>
+
+<build>
+    <plugins>
+        <plugin>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-compiler-plugin</artifactId>
+            <configuration>
+                <annotationProcessors>
+                    <annotationProcessor>
+                        org.springframework.data.ldap.repository.support.LdapAnnotationProcessor
+                    </annotationProcessor>
+                </annotationProcessors>
+
+                <!-- Recommended: Some IDE's might require this configuration to include generated sources for IDE usage -->
+                <generatedTestSourcesDirectory>target/generated-test-sources</generatedTestSourcesDirectory>
+                <generatedSourcesDirectory>target/generated-sources</generatedSourcesDirectory>
+            </configuration>
+        </plugin>
+    </plugins>
+</build>
+----
+
+Gradle::
++
+====
+[source,groovy,indent=0,subs="verbatim,quotes",role="secondary"]
+----
+dependencies {
+    implementation 'com.querydsl:querydsl-core:${querydslVersion}:jakarta'
+
+    annotationProcessor 'com.querydsl:querydsl-apt:${querydslVersion}:jakarta'
+    annotationProcessor 'org.springframework.data:spring-data-ldap'
+
+    testAnnotationProcessor 'com.querydsl:querydsl-apt:${querydslVersion}:jakarta'
+    testAnnotationProcessor 'org.springframework.data:spring-data-ldap'
+}
+
+tasks.withType(JavaCompile).configureEach {
+    options.compilerArgs += [
+            "-processor",
+            "org.springframework.data.ldap.repository.support.LdapAnnotationProcessor"]
+}
+----
+====
+======
+
+Note that the setup above shows the simplest usage omitting any other options or dependencies that your project might require.
+
+include::{commons}@data-commons::page$repositories/core-extensions-web.adoc[leveloffset=1]
+
+include::{commons}@data-commons::page$repositories/core-extensions-populators.adoc[leveloffset=1]