CORDA-3390: Allow EvolutionSerializer to handle primitive types becoming nullable. (#5661)

serialization/build.gradle

@@ -39,7 +39,8 @@ dependencies {
     testRuntimeOnly "org.junit.vintage:junit-vintage-engine:${junit_vintage_version}"
     testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:${junit_jupiter_version}"
     testRuntimeOnly "org.junit.platform:junit-platform-launcher:${junit_platform_version}"
-    
+    testRuntimeOnly "org.slf4j:slf4j-simple:$slf4j_version"
+
     testCompile "org.assertj:assertj-core:$assertj_version"
     testCompile "org.jetbrains.kotlin:kotlin-test:$kotlin_version"
     testCompile "org.mockito:mockito-core:$mockito_version"

serialization/src/main/kotlin/net/corda/serialization/internal/amqp/EvolutionSerializerFactory.kt

@@ -105,7 +105,13 @@ class DefaultEvolutionSerializerFactory(
             evolverProperties.all { (name, evolverProperty) ->
                 val propertyType = propertyTypes[name]
                 if (propertyType == null) !evolverProperty.isMandatory
-                else evolverProperty.type.observedType.asClass().isAssignableFrom(propertyType)
+                else {
+                    // Check that we can assign the remote property value to its local equivalent.
+                    // This includes assigning a primitive type to its equivalent "boxed" type.
+                    val evolverPropertyType = evolverProperty.type.observedType.asClass()
+                    evolverPropertyType.isAssignableFrom(propertyType)
+                        || (propertyType.isPrimitive && evolverPropertyType.isAssignableFrom(propertyType.kotlin.javaObjectType))
+                }
             }
         }
     }

serialization/src/test/kotlin/net/corda/serialization/internal/amqp/EvolvabilityTests.kt

@@ -23,6 +23,7 @@ import kotlin.test.assertEquals
 import net.corda.serialization.internal.amqp.custom.InstantSerializer
 import net.corda.serialization.internal.amqp.testutils.ProjectStructure.projectRootDir
 import java.math.BigInteger
+import kotlin.test.fail
 
 // To regenerate any of the binary test files do the following
 //
@@ -36,7 +37,7 @@ class EvolvabilityTests {
     // When regenerating the test files this needs to be set to the file system location of the resource files
     @Suppress("UNUSED")
     var localPath: URI = projectRootDir.toUri().resolve(
-            "serialization-test/src/test/resources/net/corda/serialization/internal/amqp")
+            "serialization/src/test/resources/net/corda/serialization/internal/amqp")
 
     companion object {
         private val DUMMY_NOTARY_NAME = CordaX500Name("Notary Service", "Zurich", "CH")
@@ -744,4 +745,27 @@ class EvolvabilityTests {
 
         assertEquals(10, deserialized.parameterized?.a)
     }
+
+    @Test
+    fun addMandatoryFieldWithAltConstructorAndMakeExistingIntFieldNullable() {
+        val sf = testDefaultFactory()
+        val resource = "EvolvabilityTests.addMandatoryFieldWithAltConstructorAndMakeExistingIntFieldNullable"
+
+        // Original version of the class as it was serialised
+        // data class CC(val a: Int)
+        // File(URI("$localPath/$resource")).writeBytes(SerializationOutput(sf).serialize(CC(1)).bytes)
+
+        data class CC(val a: Int?, val b: Int) {
+            @DeprecatedConstructorForDeserialization(1)
+            @Suppress("unused")
+            constructor(a: Int) : this(a,  42)
+        }
+
+        val url = EvolvabilityTests::class.java.getResource(resource) ?: fail("Not found!")
+        val sc2 = url.readBytes()
+        val deserializedCC = DeserializationInput(sf).deserialize(SerializedBytes<CC>(sc2))
+
+        assertEquals(1, deserializedCC.a)
+        assertEquals(42, deserializedCC.b)
+    }
 }