diff --git a/core-java-9/pom.xml b/core-java-9/pom.xml
index b29838d283..844ad6a782 100644
--- a/core-java-9/pom.xml
+++ b/core-java-9/pom.xml
@@ -60,12 +60,8 @@
 				<configuration>
 					<source>1.9</source>
 					<target>1.9</target>
-
 					<verbose>true</verbose>
-					<!-- <executable>C:\develop\jdks\jdk-9_ea122\bin\javac</executable> 
-						<compilerVersion>1.9</compilerVersion> -->
 				</configuration>
-
 			</plugin>
 
 			<plugin>
@@ -85,12 +81,7 @@
 
 
 		<!-- maven plugins -->
-		<!-- 
-		<maven-war-plugin.version>2.6</maven-war-plugin.version>
-		maven-compiler-plugin.version>3.5.1</maven-compiler-plugin.version> -->
-		<maven-compiler-plugin.version>3.6-jigsaw-SNAPSHOT</maven-compiler-plugin.version>
-
-		
+		<maven-compiler-plugin.version>3.6-jigsaw-SNAPSHOT</maven-compiler-plugin.version>	
 		<maven-surefire-plugin.version>2.19.1</maven-surefire-plugin.version>
 
 		<!-- testing -->
diff --git a/core-java-9/src/test/java/com/baeldung/java9/MultiResultionImageTest.java b/core-java-9/src/test/java/com/baeldung/java9/MultiResultionImageTest.java
index d6c16b91bc..a00646e4db 100644
--- a/core-java-9/src/test/java/com/baeldung/java9/MultiResultionImageTest.java
+++ b/core-java-9/src/test/java/com/baeldung/java9/MultiResultionImageTest.java
@@ -1,6 +1,5 @@
 package com.baeldung.java9;
-
-import static org.junit.Assert.assertTrue;
+
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertSame;
 
diff --git a/core-java-9/src/test/java/com/baeldung/java9/OptionalToStreamTest.java b/core-java-9/src/test/java/com/baeldung/java9/OptionalToStreamTest.java
new file mode 100644
index 0000000000..56b4bb7b8c
--- /dev/null
+++ b/core-java-9/src/test/java/com/baeldung/java9/OptionalToStreamTest.java
@@ -0,0 +1,21 @@
+package com.baeldung.java9;
+
+import java.util.Optional;
+import java.util.stream.Stream;
+
+import org.junit.Test;
+import static org.junit.Assert.assertEquals;
+
+public class OptionalToStreamTest {
+
+    @Test
+    public void testOptionalToStream() {
+        Optional<String> op = Optional.ofNullable("String value");
+        Stream<String> strOptionalStream = op.stream();
+        Stream<String> filteredStream = strOptionalStream.filter((str) -> {
+            return str != null && str.startsWith("String");
+        });
+        assertEquals(1, filteredStream.count());
+
+    }
+}
diff --git a/core-java-9/src/test/java/com/baeldung/java9/SetExamplesTest.java b/core-java-9/src/test/java/com/baeldung/java9/SetExamplesTest.java
new file mode 100644
index 0000000000..0f8db83d9c
--- /dev/null
+++ b/core-java-9/src/test/java/com/baeldung/java9/SetExamplesTest.java
@@ -0,0 +1,26 @@
+package com.baeldung.java9;
+
+import java.util.Set;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class SetExamplesTest {
+
+    @Test
+    public void testUnmutableSet() {
+        Set<String> strKeySet = Set.of("key1", "key2", "key3");
+        try {
+            strKeySet.add("newKey");
+        } catch (UnsupportedOperationException uoe) {
+        }
+        assertEquals(strKeySet.size(), 3);
+    }
+
+    @Test
+    public void testArrayToSet() {
+        Integer[] intArray = new Integer[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 };
+        Set<Integer> intSet = Set.of(intArray);
+        assertEquals(intSet.size(), intArray.length);
+    }
+}