BAEL-4384: Invoke a private method using reflection (#10470)

* - initial commit of sample code

* BAEL-4209:  Moving the localized exception module into core-java-exceptions-3.

* BAEL-4209: Removed the old files for localizing exception messages.

* Added test case to explain invoking a private method.

* Made the code example more useful so we don't look like we're hacking another framework.

* Forgot to make the test class and method package-private.

* Incorporated Spring ReflectionTestUtils into the code sample.

* Updated the Spring Test version to match the article.

core-java-modules/core-java-reflection-2/src/main/java/com/baeldung/reflection/access/privatemethods/LongArrayUtil.java

@@ -0,0 +1,18 @@
+package com.baeldung.reflection.access.privatemethods;
+
+public class LongArrayUtil {
+
+    public static int indexOf(long[] array, long target) {
+        return indexOf(array, target, 0, array.length);
+    }
+
+    private static int indexOf(long[] array, long target, int start, int end) {
+        for (int i = start; i < end; i++) {
+            if (array[i] == target) {
+                return i;
+            }
+        }
+        return -1;
+    }
+
+}