BAEL-2323 Adding files for native keyword tutorial (#5913)

* BAEL-2323 Adding files for native keyword tutorial

* junit test files and native library

* update test method name

core-java/src/main/java/com/baeldung/nativekeyword/DateTimeUtils.java

@@ -0,0 +1,10 @@
+package com.baeldung.nativekeyword;
+
+public class DateTimeUtils {
+
+    public native String getSystemTime();
+
+    static {
+        System.loadLibrary("nativedatetimeutils");
+    }
+}

core-java/src/main/java/com/baeldung/nativekeyword/NativeMainApp.java

@@ -0,0 +1,11 @@
+package com.baeldung.nativekeyword;
+
+import com.baeldung.nativekeyword.DateTimeUtils;
+
+public class NativeMainApp {
+    public static void main(String[] args) {
+        DateTimeUtils dateTimeUtils = new DateTimeUtils();
+        String input = dateTimeUtils.getSystemTime();
+        System.out.println("System time is : " + input);
+    }
+}

core-java/src/test/java/com/baeldung/nativekeyword/DateTimeUtilsManualTest.java

@@ -0,0 +1,27 @@
+package com.baeldung.nativekeyword;
+
+import static org.junit.Assert.assertNotNull;
+
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.slf4j.Logger;
+
+public class DateTimeUtilsManualTest {
+
+    private static final Logger LOG = org.slf4j.LoggerFactory.getLogger(DateTimeUtilsManualTest.class);
+
+    @BeforeClass
+    public static void setUpClass() {
+        System.loadLibrary("msvcr100");
+        System.loadLibrary("libgcc_s_sjlj-1");
+        System.loadLibrary("libstdc++-6");
+        System.loadLibrary("nativedatetimeutils");
+    }
+
+    @Test
+    public void givenNativeLibsLoaded_thenNativeMethodIsAccessible() {
+        DateTimeUtils dateTimeUtils = new DateTimeUtils();
+        LOG.info("System time is : " + dateTimeUtils.getSystemTime());
+        assertNotNull(dateTimeUtils.getSystemTime());
+    }
+}