diff --git a/testing-modules/testing-assertions/pom.xml b/testing-modules/testing-assertions/pom.xml
index 1f2b4e335d..1da53bd77e 100644
--- a/testing-modules/testing-assertions/pom.xml
+++ b/testing-modules/testing-assertions/pom.xml
@@ -4,18 +4,6 @@
     <modelVersion>4.0.0</modelVersion>
     <artifactId>testing-assertions</artifactId>
     <version>0.0.1-SNAPSHOT</version>
-    <build>
-        <plugins>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-compiler-plugin</artifactId>
-                <configuration>
-                    <source>9</source>
-                    <target>9</target>
-                </configuration>
-            </plugin>
-        </plugins>
-    </build>
 
     <parent>
         <groupId>com.baeldung</groupId>
diff --git a/testing-modules/testing-assertions/src/test/java/com/baeldung/assertnestedmap/AssertNestedMapUnitTest.java b/testing-modules/testing-assertions/src/test/java/com/baeldung/assertnestedmap/AssertNestedMapUnitTest.java
index 7c48a5eb4a..ceef5efdd2 100644
--- a/testing-modules/testing-assertions/src/test/java/com/baeldung/assertnestedmap/AssertNestedMapUnitTest.java
+++ b/testing-modules/testing-assertions/src/test/java/com/baeldung/assertnestedmap/AssertNestedMapUnitTest.java
@@ -3,6 +3,7 @@ package com.baeldung.assertnestedmap;
 
 import org.junit.jupiter.api.Test;
 
+import java.util.HashMap;
 import java.util.Map;
 
 import static com.baeldung.assertnestedmap.matchers.NestedMapMatcher.hasNestedMapEntry;
@@ -13,16 +14,22 @@ import static org.junit.jupiter.api.Assertions.*;
 public class AssertNestedMapUnitTest {
     @Test
     void givenNestedMap_whenUseJupiterAssertTrueWithoutCasting_thenTest() {
-        Map<String, Object> innerMap = Map.of("city", "Chicago");
-        Map<String, Map<String, Object>> outerMap = Map.of("address", innerMap);
+        Map<String, Object> innerMap = new HashMap<>();
+        innerMap.put("city", "Chicago");
+
+        Map<String, Map<String, Object>> outerMap = new HashMap<>();
+        outerMap.put("address", innerMap);
 
         assertTrue(outerMap.containsKey("address") && outerMap.get("address").get("city").equals("Chicago"));
     }
 
     @Test
     void givenNestedMap_whenUseJupiterAssertAllAndAssertTrue_thenTest() {
-        Map<String, Object> innerMap = Map.of("city", "Chicago");
-        Map<String, Map<String, Object>> outerMap = Map.of("address", innerMap);
+        Map<String, Object> innerMap = new HashMap<>();
+        innerMap.put("city", "Chicago");
+
+        Map<String, Map<String, Object>> outerMap = new HashMap<>();
+        outerMap.put("address", innerMap);
 
         assertAll(
           () -> assertTrue(outerMap.containsKey("address")),
@@ -32,8 +39,11 @@ public class AssertNestedMapUnitTest {
 
     @Test
     void givenNestedMap_whenUseJupiterAssertTrueWithCasting_thenTest() {
-        Map<String, Object> innerMap = Map.of("city", "Chicago");
-        Map<String, Object> outerMap = Map.of("address", innerMap);
+        Map<String, Object> innerMap = new HashMap<>();
+        innerMap.put("city", "Chicago");
+
+        Map<String, Object> outerMap = new HashMap<>();
+        outerMap.put("address", innerMap);
 
         assertTrue(outerMap.containsKey("address")
                 && ((Map<String, Object>)outerMap.get("address")).get("city").equals("Chicago"));
@@ -41,8 +51,12 @@ public class AssertNestedMapUnitTest {
 
     @Test
     void givenNestedMap_whenUseHamcrestAssertThat_thenTest() {
-        Map<String, Object> innerMap = Map.of("city", "Chicago");
-        Map<String, Map<String, Object>> outerMap = Map.of("address", innerMap);
+        Map<String, Object> innerMap = new HashMap<>();
+        innerMap.put("city", "Chicago");
+
+        Map<String, Map<String, Object>> outerMap = new HashMap<>();
+        outerMap.put("address", innerMap);
+
         assertAll(
           () -> assertThat(outerMap, hasKey("address")),
           () -> assertThat(outerMap.get("address"), hasEntry("city", "Chicago"))
@@ -51,42 +65,46 @@ public class AssertNestedMapUnitTest {
 
     @Test
     void givenNestedMapOfStringAndObject_whenUseHamcrestAssertThat_thenTest() {
-        Map<String, Object> innerMap = Map.of("city", "Chicago");
-        Map<String, Map<String, Object>> outerMap = Map.of("address", innerMap);
+        Map<String, Object> innerMap = new HashMap<>();
+        innerMap.put("city", "Chicago");
+
+        Map<String, Map<String, Object>> outerMap = new HashMap<>();
+        outerMap.put("address", innerMap);
 
         assertThat(outerMap, hasEntry(equalTo("address"), hasEntry("city", "Chicago")));
     }
 
     @Test
     void givenNestedMapOfStringAndObject_whenUseHamcrestAssertThatAndCustomMatcher_thenTest() {
-        Map<String, Object> innerMap = Map.of
-          (
-            "city", "Chicago",
-            "zip", "10005"
-          );
-        Map<String, Map<String, Object>> outerMap = Map.of("address", innerMap);
+        Map<String, Object> innerMap = new HashMap<>();
+        innerMap.put("city", "Chicago");
+        innerMap.put("zip", "10005");
+
+        Map<String, Map<String, Object>> outerMap = new HashMap<>();
+        outerMap.put("address", innerMap);
 
         assertThat(outerMap, hasNestedMapEntry("address", innerMap));
     }
 
     @Test
     void givenOuterMapOfStringAndObjectAndInnerMap_whenUseHamcrestAssertThatAndCustomMatcher_thenTest() {
-        Map<String, Object> innerMap = Map.of
-          (
-            "city", "Chicago",
-            "zip", "10005"
-          );
-        Map<String, Object> outerMap = Map.of("address", innerMap);
+        Map<String, Object> innerMap = new HashMap<>();
+        innerMap.put("city", "Chicago");
+        innerMap.put("zip", "10005");
+
+        Map<String, Object> outerMap = new HashMap<>();
+        outerMap.put("address", innerMap);
 
         assertThat(outerMap, hasNestedMapEntry("address", innerMap));
     }
 
     @Test
     void givenNestedMap_whenUseHamcrestAssertThatWithCasting_thenTest() {
-        Map<String, Object> innerMap = Map.of("city", "Chicago");
-        Map<String, Object> outerMap = Map.of("address", innerMap);
+        Map<String, Object> innerMap = new HashMap<>();
+        innerMap.put("city", "Chicago");
+        Map<String, Object> outerMap = new HashMap<>();
+        outerMap.put("address", innerMap);
 
         assertThat((Map<String, Object>)outerMap.get("address"), hasEntry("city", "Chicago"));
     }
-
 }