Add test to check references are restored correctly

node/src/integration-test/kotlin/net/corda/node/MockNetworkCustomSerializerCheckpointTest.kt

@@ -29,17 +29,30 @@ class MockNetworkCustomSerializerCheckpointTest{
         mockNetwork.stopNodes()
     }
 
+    // Tests
+
     @Test(timeout = 300_000)
     fun `flow suspend with custom kryo serializer`() {
         val node = mockNetwork.createPartyNode()
         val expected = 5
-        val actual = node.startFlow(TestFlow(5)).get()
+        val actual = node.startFlow(TestFlowWithDifficultToSerializeLocalVariable(5)).get()
 
         Assertions.assertThat(actual).isEqualTo(expected)
     }
 
+    @Test(timeout = 300_000)
+    fun `check references are restored correctly`() {
+        val node = mockNetwork.createPartyNode()
+        val expectedReference = immutableMapOf(1 to 1)
+        val actualReference = node.startFlow(TestFlowCheckingReferencesWork(expectedReference)).get()
+
+        Assertions.assertThat(actualReference).isSameAs(expectedReference)
+    }
+
+    // Flows
+
     @StartableByRPC
-    class TestFlow(private val purchase: Int) : FlowLogic<Int>() {
+    class TestFlowWithDifficultToSerializeLocalVariable(private val purchase: Int) : FlowLogic<Int>() {
         @Suspendable
         override fun call(): Int {
 
@@ -54,14 +67,38 @@ class MockNetworkCustomSerializerCheckpointTest{
         }
     }
 
+    @StartableByRPC
+    class TestFlowCheckingReferencesWork<T>(private val reference: T) : FlowLogic<T>() {
+
+        private val referenceField = reference
+
+        @Suspendable
+        override fun call(): T {
+
+            val ref = referenceField
+
+            // Force a checkpoint
+            sleep(Duration.ofSeconds(0), maySkipCheckpoint = false)
+
+            // Check all objects refer to same object
+            Assertions.assertThat(reference).isSameAs(referenceField)
+            Assertions.assertThat(referenceField).isSameAs(ref)
+
+            // Return deserialized object
+            return ref
+        }
+    }
+
+    // Custom serializers
+
     @Suppress("unused")
-    class TestSerializer : SerializationCustomSerializer<ImmutableMap<String, Int>, HashMap<String, Int>> {
-        override fun toProxy(obj: ImmutableMap<String, Int>): HashMap<String, Int> {
-            val proxy = HashMap<String, Int>()
+    class TestSerializer : SerializationCustomSerializer<ImmutableMap<Any, Any>, HashMap<Any, Any>> {
+        override fun toProxy(obj: ImmutableMap<Any, Any>): HashMap<Any, Any> {
+            val proxy = HashMap<Any, Any>()
             return obj.toMap(proxy)
         }
 
-        override fun fromProxy(proxy: HashMap<String, Int>): ImmutableMap<String, Int> {
+        override fun fromProxy(proxy: HashMap<Any, Any>): ImmutableMap<Any, Any> {
             return proxy.toImmutableMap()
         }
     }