fix: handle unknown enums in readFlat

hollow/src/main/java/com/netflix/hollow/core/write/objectmapper/HollowObjectTypeMapper.java

@@ -698,7 +698,12 @@ public void copy(Object pojo, GenericHollowObject rec) {
                 case ENUM_NAME:
                     String enumNameValue = rec.getString(fieldName);
                     if (enumNameValue != null) {
-                        unsafe.putObject(pojo, fieldOffset, Enum.valueOf((Class<Enum>) type, enumNameValue));
+                        try {
+                            Object val = Enum.valueOf((Class<Enum>) type, enumNameValue);
+                            unsafe.putObject(pojo, fieldOffset, val);
+                        } catch (IllegalArgumentException e) {
+                            // If the enum value is not found, we leave the field as null
+                        }
                     }
                     break;
                 case REFERENCE:
@@ -715,7 +720,10 @@ public void copy(Object pojo, GenericHollowObject rec) {
         private Object parseBoxedWrapper(GenericHollowObject record) {
             switch (fieldType) {
                 case BOOLEAN:
-                    return Boolean.valueOf(record.getBoolean(fieldName));
+                    if (record.isNull(fieldName)) {
+                        return null;
+                    }
+                    return record.getBoolean(fieldName);
                 case INT:
                     int intValue = record.getInt(fieldName);
                     if (intValue == Integer.MIN_VALUE) {
@@ -767,7 +775,11 @@ private Object parseBoxedWrapper(GenericHollowObject record) {
                     if (enumName == null) {
                         return null;
                     }
-                    return Enum.valueOf((Class<Enum>) clazz, enumName);
+                    try {
+                        return Enum.valueOf((Class<Enum>) clazz, enumName);
+                    } catch (IllegalArgumentException e) {
+                        return null;
+                    }
                 case DATE_TIME: {
                     long dateValue = record.getLong(fieldName);
                     if (dateValue == Long.MIN_VALUE) {
@@ -783,7 +795,10 @@ private Object parseBoxedWrapper(GenericHollowObject record) {
         private Object parseBoxedWrapper(FlatRecordTraversalObjectNode record) {
             switch (fieldType) {
                 case BOOLEAN:
-                    return record.getFieldValueBooleanBoxed(fieldName);
+                    if (record.isFieldNull(fieldName)) {
+                        return null;
+                    }
+                    return record.getFieldValueBoolean(fieldName);
                 case INT:
                     return record.getFieldValueIntBoxed(fieldName);
                 case SHORT:
@@ -819,7 +834,11 @@ private Object parseBoxedWrapper(FlatRecordTraversalObjectNode record) {
                     if (enumName == null) {
                         return null;
                     }
-                    return Enum.valueOf((Class<Enum>) clazz, enumName);
+                    try {
+                        return Enum.valueOf((Class<Enum>) clazz, enumName);
+                    } catch (IllegalArgumentException e) {
+                        return null;
+                    }
                 case DATE_TIME: {
                     long dateValue = record.getFieldValueLong(fieldName);
                     if (dateValue == Long.MIN_VALUE) {
@@ -975,7 +994,12 @@ private void copy(Object obj, FlatRecordTraversalObjectNode node) {
                 case ENUM_NAME: {
                     String value = node.getFieldValueString(fieldName);
                     if (value != null) {
-                        unsafe.putObject(obj, fieldOffset, Enum.valueOf((Class) type, value));
+                        try {
+                            Object val = Enum.valueOf((Class) type, value);
+                            unsafe.putObject(obj, fieldOffset, val);
+                        } catch (IllegalArgumentException e) {
+                            // If the enum value is not found, we leave the field as null
+                        }
                     }
                     break;
                 }

hollow/src/test/java/com/netflix/hollow/core/write/objectmapper/HollowObjectMapperFlatRecordParserTest.java

@@ -28,6 +28,7 @@ public void setUp() {
     mapper.initializeTypeState(TypeWithCollections.class);
     mapper.initializeTypeState(VersionedType2.class);
     mapper.initializeTypeState(SpecialWrapperTypesTest.class);
+    mapper.initializeTypeState(UnknownEnumTypeTestV2.class);
 
     flatRecordWriter = new FlatRecordWriter(
         mapper.getStateEngine(), new FakeHollowSchemaIdentifierMapper(mapper.getStateEngine()));
@@ -76,6 +77,45 @@ public void roundTripPreservesNullability() {
     Assert.assertEquals(obj, roundTrippedResult);
   }
 
+  @Test
+  public void unknownEnums() {
+    HollowObjectMapper readerMapper = new HollowObjectMapper(new HollowWriteStateEngine());
+    readerMapper.initializeTypeState(UnknownEnumTypeTestV1.class);
+
+    UnknownEnumTypeTestV2 obj = new UnknownEnumTypeTestV2();
+    obj.id = 1;
+    obj.enumField = AnEnum.SOME_VALUE_C;
+
+    flatRecordWriter.reset();
+    mapper.writeFlat(obj, flatRecordWriter);
+    FlatRecord fr = flatRecordWriter.generateFlatRecord();
+
+    UnknownEnumTypeTestV1 result = readerMapper.readFlat(fr);
+    Assert.assertNull(result.enumField);
+  }
+
+  @Test
+  public void nullableBoxedWrappers() {
+    TypeWithAllSimpleTypes obj = new TypeWithAllSimpleTypes();
+    // set PK
+    obj.boxedIntegerField = 1;
+    obj.stringField = "hello";
+    // all inlined values are null
+
+    flatRecordWriter.reset();
+    mapper.writeFlat(obj, flatRecordWriter);
+    FlatRecord fr = flatRecordWriter.generateFlatRecord();
+
+    TypeWithAllSimpleTypes result = mapper.readFlat(fr);
+    Assert.assertNull(result.boxedBooleanField);
+    Assert.assertNull(result.boxedDoubleField);
+    Assert.assertNull(result.boxedFloatField);
+    Assert.assertNull(result.boxedLongField);
+    Assert.assertNull(result.boxedShortField);
+    Assert.assertNull(result.boxedByteField);
+    Assert.assertNull(result.boxedCharField);
+  }
+
   @Test
   public void testSimpleTypes() {
     TypeWithAllSimpleTypes typeWithAllSimpleTypes = new TypeWithAllSimpleTypes();
@@ -605,6 +645,11 @@ public static class SubValue {
     public String anotherValue;
   }
 
+  enum OlderAnEnum {
+    SOME_VALUE_A,
+    SOME_VALUE_B,
+  }
+
   enum AnEnum {
     SOME_VALUE_A,
     SOME_VALUE_B,
@@ -625,6 +670,22 @@ enum ComplexEnum {
     }
   }
 
+  @HollowTypeName(name = "UnknownEnumTypeTest")
+  @HollowPrimaryKey(fields = {"id"})
+  static class UnknownEnumTypeTestV1 {
+    long id;
+    @HollowTypeName(name = "AnEnum")
+    OlderAnEnum enumField;
+  }
+
+  @HollowTypeName(name = "UnknownEnumTypeTest")
+  @HollowPrimaryKey(fields = {"id"})
+  static class UnknownEnumTypeTestV2 {
+    long id;
+    @HollowTypeName(name = "AnEnum")
+    AnEnum enumField;
+  }
+
   @HollowTypeName(name = "SpecialWrapperTypesTest")
   @HollowPrimaryKey(fields = {"id"})
   static class SpecialWrapperTypesTest {