Feature/kotlin equality (#1831)

* Add project for hibernate immutable article
Add Event entity
Add hibernate configuration file
Add hibernateutil for configuration
Add test to match snippets from article

* Update master

* Add simplet test to check Kotlin rerence vs strutural equality

* Update README

kotlin/README.md

@@ -3,3 +3,5 @@
 - [Introduction to the Kotlin Language](http://www.baeldung.com/kotlin)
 - [A guide to the “when{}” block in Kotlin](http://www.baeldung.com/kotlin-when)
 - [Comprehensive Guide to Null Safety in Kotlin](http://www.baeldung.com/kotlin-null-safety)
+- [Kotlin Java Interoperability](http://www.baeldung.com/kotlin-java-interoperability)
+- [Difference Between “==” and “===” in Kotlin]()

kotlin/src/test/kotlin/com/baeldung/kotlin/EqualityTest.kt

@@ -0,0 +1,26 @@
+package com.baeldung.kotlin
+
+import org.junit.Test
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+class EqualityTest {
+
+    // Checks referential equality
+    @Test
+    fun givenTwoIntegers_whenCheckReference_thenEqualReference() {
+        val a = Integer(10)
+        val b = Integer(10)
+
+        assertFalse(a === b)
+    }
+
+    // Checks structural equality
+    @Test
+    fun givenTwoIntegers_whenCheckValue_thenStructurallyEqual() {
+        val a = Integer(10)
+        val b = Integer(10)
+
+        assertTrue(a == b)
+    }
+}