diff --git a/spring-security-modules/spring-security-ldap/pom.xml b/spring-security-modules/spring-security-ldap/pom.xml
index 9f4f3b4106..0da7fc27c5 100644
--- a/spring-security-modules/spring-security-ldap/pom.xml
+++ b/spring-security-modules/spring-security-ldap/pom.xml
@@ -10,8 +10,9 @@
 
     <parent>
         <groupId>com.baeldung</groupId>
-        <artifactId>spring-security-modules</artifactId>
+        <artifactId>parent-boot-3</artifactId>
         <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-boot-3</relativePath>
     </parent>
 
     <dependencies>
@@ -64,6 +65,11 @@
                 </exclusion>
             </exclusions>
         </dependency>
+        <dependency>
+            <groupId>com.unboundid</groupId>
+            <artifactId>unboundid-ldapsdk</artifactId>
+            <version>${unboundid-ldapsdk.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -78,6 +84,8 @@
 
     <properties>
         <apacheds.version>1.5.5</apacheds.version>
+        <start-class>com.baeldung.SampleLDAPApplication</start-class>
+        <unboundid-ldapsdk.version>4.0.10</unboundid-ldapsdk.version>
     </properties>
 
 </project>
\ No newline at end of file
diff --git a/spring-security-modules/spring-security-ldap/src/main/java/com/baeldung/SampleLDAPApplication.java b/spring-security-modules/spring-security-ldap/src/main/java/com/baeldung/SampleLDAPApplication.java
index 2d619cccfa..af1dd350a8 100644
--- a/spring-security-modules/spring-security-ldap/src/main/java/com/baeldung/SampleLDAPApplication.java
+++ b/spring-security-modules/spring-security-ldap/src/main/java/com/baeldung/SampleLDAPApplication.java
@@ -3,9 +3,6 @@ package com.baeldung;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
-import org.springframework.context.annotation.Bean;
-import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
-import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
 
 /**
  * Main Application Class - uses Spring Boot. Just run this as a normal Java
diff --git a/spring-security-modules/spring-security-ldap/src/main/java/com/baeldung/config/SecurityConfig.java b/spring-security-modules/spring-security-ldap/src/main/java/com/baeldung/config/SecurityConfig.java
index 78e4dff29c..b76b1d945b 100644
--- a/spring-security-modules/spring-security-ldap/src/main/java/com/baeldung/config/SecurityConfig.java
+++ b/spring-security-modules/spring-security-ldap/src/main/java/com/baeldung/config/SecurityConfig.java
@@ -6,7 +6,7 @@ import org.springframework.ldap.core.support.BaseLdapPathContextSource;
 import org.springframework.security.authentication.AuthenticationManager;
 import org.springframework.security.config.annotation.web.builders.HttpSecurity;
 import org.springframework.security.config.ldap.LdapBindAuthenticationManagerFactory;
-import org.springframework.security.ldap.server.ApacheDSContainer;
+import org.springframework.security.ldap.server.UnboundIdContainer;
 import org.springframework.security.ldap.userdetails.DefaultLdapAuthoritiesPopulator;
 import org.springframework.security.ldap.userdetails.LdapAuthoritiesPopulator;
 import org.springframework.security.web.SecurityFilterChain;
@@ -19,8 +19,8 @@ import org.springframework.security.web.SecurityFilterChain;
 public class SecurityConfig {
 
     @Bean
-    ApacheDSContainer ldapContainer() throws Exception {
-        return new ApacheDSContainer("dc=baeldung,dc=com", "classpath:users.ldif");
+    UnboundIdContainer  ldapContainer() throws Exception {
+        return new UnboundIdContainer("dc=baeldung,dc=com", "classpath:users.ldif");
     }
 
     @Bean
@@ -41,18 +41,13 @@ public class SecurityConfig {
 
     @Bean
     public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
-        http.authorizeRequests()
-            .antMatchers("/", "/home", "/css/**")
-            .permitAll()
-            .anyRequest()
-            .authenticated()
-            .and()
-            .formLogin()
-            .loginPage("/login")
-            .permitAll()
-            .and()
-            .logout()
-            .logoutSuccessUrl("/");
-        return http.build();
+        return http.authorizeHttpRequests(auth -> auth
+                .requestMatchers("/", "/home", "/css/**")
+                .permitAll()
+                .anyRequest()
+                .authenticated())
+            .formLogin(httpSecurityFormLoginConfigurer ->
+                httpSecurityFormLoginConfigurer.loginPage("/login").permitAll())
+            .logout(logout -> logout.logoutSuccessUrl("/")).build();
     }
 }
diff --git a/spring-security-modules/spring-security-ldap/src/main/java/org/apache/directory/server/core/avltree/ArrayMarshaller.java b/spring-security-modules/spring-security-ldap/src/main/java/org/apache/directory/server/core/avltree/ArrayMarshaller.java
new file mode 100644
index 0000000000..78c1e69ee7
--- /dev/null
+++ b/spring-security-modules/spring-security-ldap/src/main/java/org/apache/directory/server/core/avltree/ArrayMarshaller.java
@@ -0,0 +1,172 @@
+/*
+ * Copyright 2002-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.directory.server.core.avltree;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.util.Comparator;
+import org.apache.directory.shared.ldap.util.StringTools;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Class to serialize the Array data.
+ *
+ * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
+ * @version $Rev$, $Date$
+ */
+@SuppressWarnings("unchecked")
+public class ArrayMarshaller<E> implements Marshaller<ArrayTree<E>> {
+
+	/** static logger */
+	private static final Logger LOG = LoggerFactory.getLogger(ArrayMarshaller.class);
+
+	/** used for serialized form of an empty AvlTree */
+	private static final byte[] EMPTY_TREE = new byte[1];
+
+	/** marshaller to be used for marshalling the keys */
+	private Marshaller<E> keyMarshaller;
+
+	/** key Comparator for the AvlTree */
+	private Comparator<E> comparator;
+
+	/**
+	 * Creates a new instance of AvlTreeMarshaller with a custom key Marshaller.
+	 * @param comparator Comparator to be used for key comparision
+	 * @param keyMarshaller marshaller for keys
+	 */
+	public ArrayMarshaller(Comparator<E> comparator, Marshaller<E> keyMarshaller) {
+		this.comparator = comparator;
+		this.keyMarshaller = keyMarshaller;
+	}
+
+	/**
+	 * Creates a new instance of AvlTreeMarshaller with the default key Marshaller which
+	 * uses Java Serialization.
+	 * @param comparator Comparator to be used for key comparision
+	 */
+	public ArrayMarshaller(Comparator<E> comparator) {
+		this.comparator = comparator;
+		this.keyMarshaller = (Marshaller<E>) DefaultMarshaller.INSTANCE;
+	}
+
+	/**
+	 * Marshals the given tree to bytes
+	 * @param tree the tree to be marshalled
+	 */
+	public byte[] serialize(ArrayTree<E> tree) {
+		if ((tree == null) || (tree.size() == 0)) {
+			return EMPTY_TREE;
+		}
+
+		ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
+		DataOutputStream out = new DataOutputStream(byteStream);
+		byte[] data = null;
+
+		try {
+			out.writeByte(0); // represents the start of an Array byte stream
+			out.writeInt(tree.size());
+
+			for (int position = 0; position < tree.size(); position++) {
+				E value = tree.get(position);
+				byte[] bytes = this.keyMarshaller.serialize(value);
+
+				// Write the key length
+				out.writeInt(bytes.length);
+
+				// Write the key if its length is not null
+				if (bytes.length != 0) {
+					out.write(bytes);
+				}
+			}
+
+			out.flush();
+			data = byteStream.toByteArray();
+
+			// Try to deserialize, just to see
+			try {
+				deserialize(data);
+			}
+			catch (NullPointerException npe) {
+				System.out.println("Bad serialization, tree : [" + StringTools.dumpBytes(data) + "]");
+				throw npe;
+			}
+
+			out.close();
+		}
+		catch (IOException ex) {
+			ex.printStackTrace();
+		}
+
+		return data;
+	}
+
+	/**
+	 * Creates an Array from given bytes of data.
+	 * @param data byte array to be converted into an array
+	 */
+	public ArrayTree<E> deserialize(byte[] data) throws IOException {
+		try {
+			if ((data == null) || (data.length == 0)) {
+				throw new IOException("Null or empty data array is invalid.");
+			}
+
+			if ((data.length == 1) && (data[0] == 0)) {
+				E[] array = (E[]) new Object[] {};
+				ArrayTree<E> tree = new ArrayTree<E>(this.comparator, array);
+				return tree;
+			}
+
+			ByteArrayInputStream bin = new ByteArrayInputStream(data);
+			DataInputStream din = new DataInputStream(bin);
+
+			byte startByte = din.readByte();
+
+			if (startByte != 0) {
+				throw new IOException("wrong array serialized data format");
+			}
+
+			int size = din.readInt();
+			E[] nodes = (E[]) new Object[size];
+
+			for (int i = 0; i < size; i++) {
+				// Read the object's size
+				int dataSize = din.readInt();
+
+				if (dataSize != 0) {
+					byte[] bytes = new byte[dataSize];
+
+					din.read(bytes);
+					E key = this.keyMarshaller.deserialize(bytes);
+					nodes[i] = key;
+				}
+			}
+
+			ArrayTree<E> arrayTree = new ArrayTree<E>(this.comparator, nodes);
+
+			return arrayTree;
+		}
+		catch (NullPointerException npe) {
+			System.out.println("Bad tree : [" + StringTools.dumpBytes(data) + "]");
+			throw npe;
+		}
+	}
+
+}
\ No newline at end of file