Upgrading maven-dependency-plugin, maven-checkstyle-plugin and maven-…

…jxr-plugin

pom.xml

@@ -1513,7 +1513,7 @@ under the License.
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-dependency-plugin</artifactId>
-          <version>3.8.0</version>
+          <version>3.8.1</version>
           <configuration>
             <outputDirectory>${bundles.directory}</outputDirectory>
             <artifactItems>
@@ -1687,7 +1687,7 @@ under the License.
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-checkstyle-plugin</artifactId>
-          <version>3.5.0</version>
+          <version>3.6.0</version>
           <configuration>
             <configLocation>${rootpom.basedir}/src/main/resources/org/apache/syncope/checkstyle.xml</configLocation>
             <includeTestSourceDirectory>true</includeTestSourceDirectory>
@@ -2070,7 +2070,7 @@ under the License.
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-jxr-plugin</artifactId>
-        <version>3.5.0</version>
+        <version>3.6.0</version>
       </plugin>
     </plugins>
   </reporting>

src/main/asciidoc/reference-guide/configuration/highavailability.adoc

@@ -34,8 +34,18 @@ The default configuration in `core.properties` is
 persistence.remoteCommitProvider=sjvm
 ....
 
-which is suited for single JVM installations; with multiple instances, more options like as TCP or JMS are available;
-see the OpenJPA documentation for reference.
+which is suited for single JVM installations; with multiple instances, more options like as TCP, JMS or Kubernetes
+are available; see the OpenJPA documentation for reference.
+
+With multiple instances, ensure to add the following dependency to `core/pom.xml`:
+
+[source,xml,subs="verbatim,attributes"]
+----
+<dependency>
+  <groupId>org.apache.commons</groupId>
+  <artifactId>commons-pool2</artifactId>
+</dependency>
+----
 
 [WARNING]
 ====