BAEL-4969: Improvement: Streams to Immutable Collections (#11026)

* add new module for java core 16

* format pom.xml

core-java-modules/core-java-16/README.md

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+### Relevant articles:
+
+- [Collect a Java Stream to an Immutable Collection](https://www.baeldung.com/java-stream-immutable-collection)

core-java-modules/core-java-16/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-java-16</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-16</name>
+    <packaging>jar</packaging>
+    <url>http://maven.apache.org</url>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+        <relativePath>../../</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven-compiler-plugin.version}</version>
+                <configuration>
+                    <source>${maven.compiler.source.version}</source>
+                    <target>${maven.compiler.target.version}</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <maven.compiler.source.version>16</maven.compiler.source.version>
+        <maven.compiler.target.version>16</maven.compiler.target.version>
+        <assertj.version>3.6.1</assertj.version>
+    </properties>
+
+</project>

core-java-modules/core-java-16/src/test/java/com/baeldung/streams/StreamToImmutableUnitTest.java

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+package com.baeldung.streams;
+
+import java.util.List;
+import java.util.stream.Stream;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class StreamToImmutableUnitTest {
+
+    @Test
+    public void whenUsingStreamToList_thenReturnImmutableList() {
+
+        List<String> immutableList = Stream.of("a", "b", "c", "d")
+            .toList();
+
+        Assertions.assertThrows(UnsupportedOperationException.class, () -> {
+            immutableList.add("e");
+        });
+
+    }
+
+}