BAEL-614 java/kotlin interop

kotlin/src/main/kotlin/com/baeldung/kotlin/ItemService.kt

@@ -24,13 +24,17 @@ class ItemManager(val categoryId: String, val dbConnection: String) {
     fun makeAnalyisOfCategory(catId: String): Unit {
         val result = if (catId == "100") "Yes" else "No"
         println(result)
-
+        `object`()
     }
 
     fun sum(a: Int, b: Int): Int {
         return a + b
     }
 
+    fun `object`(): String {
+        return "this is object"
+    }
+
 }
 
 fun main(args: Array<String>) {

kotlin/src/main/kotlin/com/baeldung/kotlin/MathematicsOperations.kt

@@ -0,0 +1,7 @@
+package com.baeldung.kotlin
+
+class MathematicsOperations {
+    fun addTwoNumbers(a: Int, b: Int): Int {
+        return a + b
+    }
+}

kotlin/src/test/java/com/baeldung/kotlin/JavaCallToKotlinTest.java

@@ -0,0 +1,17 @@
+package com.baeldung.kotlin;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class JavaCallToKotlinTest {
+    @Test
+    public void givenKotlinClass_whenCallFromJava_shouldProduceResults() {
+        //when
+        int res = new MathematicsOperations().addTwoNumbers(2, 4);
+
+        //then
+        assertEquals(6, res);
+
+    }
+}