Improve the Kotlin Jackson module

kotlin-libraries-2/src/test/kotlin/com/baeldung/kotlin/jackson/JacksonUnitTest.kt

@@ -60,6 +60,10 @@ class JacksonUnitTest {
         
         assertEquals(aMap[1], "one")   
         assertEquals(aMap[2], "two")
+
+        val sameMap = mapper.readValue<Map<Int,String>>(json)
+        assertEquals(sameMap[1], "one")
+        assertEquals(sameMap[2], "two")
     }
     
     @Test