Allow default enums with @JsonCreator

This follows the pattern for READ_UNKNOWN_ENUM_VALUES_AS_NULL from here:
https://github.com/FasterXML/jackson-databind/pull/1642/files

but for READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE

It's more tricky because it wasn't immediately apparent how to get the
configured default value on the Creator impl side. I decided to try
using the EnumResolver, which works, but am not sure what the
repercussions of that are fully though.

It works the same way, so only IllegalArgumentExceptions will trigger
default behavior, so if you have some other custom creator exception
logic that will be unaffected.

Author: dropofwill

src/main/java/com/fasterxml/jackson/databind/deser/BasicDeserializerFactory.java

@@ -1087,7 +1087,9 @@ public JsonDeserializer<?> createEnumDeserializer(DeserializationContext ctxt,
 "Invalid `@JsonCreator` annotated Enum factory method [%s]: needs to return compatible type",
 factory.toString()));
                     }
-                    deser = EnumDeserializer.deserializerForCreator(config, enumClass, factory, valueInstantiator, creatorProps);
+                    deser = EnumDeserializer.deserializerForCreator(
+                        config, enumClass, factory, valueInstantiator, creatorProps,
+                        constructEnumResolver(enumClass, config, beanDesc));
                     break;
                 }
             }

src/main/java/com/fasterxml/jackson/databind/deser/std/EnumDeserializer.java

@@ -160,7 +160,7 @@ public EnumDeserializer(EnumResolver byNameResolver) {
     @Deprecated
     public static JsonDeserializer<?> deserializerForCreator(DeserializationConfig config,
             Class<?> enumClass, AnnotatedMethod factory) {
-        return deserializerForCreator(config, enumClass, factory, null, null);
+        return deserializerForCreator(config, enumClass, factory, null, null, null);
     }
 
     /**
@@ -172,16 +172,15 @@ public static JsonDeserializer<?> deserializerForCreator(DeserializationConfig c
      * @since 2.8
      */
     public static JsonDeserializer<?> deserializerForCreator(DeserializationConfig config,
-            Class<?> enumClass, AnnotatedMethod factory,
-            ValueInstantiator valueInstantiator, SettableBeanProperty[] creatorProps)
+             Class<?> enumClass, AnnotatedMethod factory, ValueInstantiator valueInstantiator,
+             SettableBeanProperty[] creatorProps, EnumResolver byNameResolver)
     {
         if (config.canOverrideAccessModifiers()) {
             ClassUtil.checkAndFixAccess(factory.getMember(),
                     config.isEnabled(MapperFeature.OVERRIDE_PUBLIC_ACCESS_MODIFIERS));
         }
-        return new FactoryBasedEnumDeserializer(enumClass, factory,
-                factory.getParameterType(0),
-                valueInstantiator, creatorProps);
+        return new FactoryBasedEnumDeserializer(enumClass, factory, factory.getParameterType(0),
+            valueInstantiator, creatorProps, byNameResolver);
     }
 
     /**

src/main/java/com/fasterxml/jackson/databind/deser/std/FactoryBasedEnumDeserializer.java

@@ -1,6 +1,7 @@
 package com.fasterxml.jackson.databind.deser.std;
 
 import java.io.IOException;
+import java.util.Objects;
 
 import com.fasterxml.jackson.core.JacksonException;
 import com.fasterxml.jackson.core.JsonParser;
@@ -15,6 +16,7 @@
 import com.fasterxml.jackson.databind.jsontype.TypeDeserializer;
 import com.fasterxml.jackson.databind.type.LogicalType;
 import com.fasterxml.jackson.databind.util.ClassUtil;
+import com.fasterxml.jackson.databind.util.EnumResolver;
 
 /**
  * Deserializer that uses a single-String static factory method
@@ -34,6 +36,7 @@ class FactoryBasedEnumDeserializer
     protected final JsonDeserializer<?> _deser;
     protected final ValueInstantiator _valueInstantiator;
     protected final SettableBeanProperty[] _creatorProps;
+    protected final Enum<?> _defaultValue;
 
     protected final boolean _hasArgs;
 
@@ -45,7 +48,8 @@ class FactoryBasedEnumDeserializer
     private transient volatile PropertyBasedCreator _propCreator;
 
     public FactoryBasedEnumDeserializer(Class<?> cls, AnnotatedMethod f, JavaType paramType,
-            ValueInstantiator valueInstantiator, SettableBeanProperty[] creatorProps)
+            ValueInstantiator valueInstantiator, SettableBeanProperty[] creatorProps,
+            EnumResolver enumResolver)
     {
         super(cls);
         _factory = f;
@@ -56,6 +60,13 @@ public FactoryBasedEnumDeserializer(Class<?> cls, AnnotatedMethod f, JavaType pa
         _deser = null;
         _valueInstantiator = valueInstantiator;
         _creatorProps = creatorProps;
+        _defaultValue = Objects.nonNull(enumResolver)? enumResolver.getDefaultValue() : null;
+    }
+
+    public FactoryBasedEnumDeserializer(Class<?> cls, AnnotatedMethod f, JavaType paramType,
+            ValueInstantiator valueInstantiator, SettableBeanProperty[] creatorProps)
+    {
+        this(cls, f, paramType, valueInstantiator, creatorProps, null);
     }
 
     /**
@@ -70,6 +81,7 @@ public FactoryBasedEnumDeserializer(Class<?> cls, AnnotatedMethod f)
         _deser = null;
         _valueInstantiator = null;
         _creatorProps = null;
+        _defaultValue = null;
     }
 
     protected FactoryBasedEnumDeserializer(FactoryBasedEnumDeserializer base,
@@ -80,6 +92,7 @@ protected FactoryBasedEnumDeserializer(FactoryBasedEnumDeserializer base,
         _hasArgs = base._hasArgs;
         _valueInstantiator = base._valueInstantiator;
         _creatorProps = base._creatorProps;
+        _defaultValue = base._defaultValue;
 
         _deser = deser;
     }
@@ -202,6 +215,10 @@ public Object deserialize(JsonParser p, DeserializationContext ctxt) throws IOEx
                 if (ctxt.isEnabled(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL)) {
                     return null;
                 }
+
+                if (ctxt.isEnabled(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE)) {
+                    return _defaultValue;
+                }
                 // 12-Oct-2021, tatu: Should probably try to provide better exception since
                 //   we likely hit argument incompatibility... Or can this happen?
             }

src/test/java/com/fasterxml/jackson/databind/deser/creators/EnumCreatorTest.java

@@ -125,7 +125,8 @@ public JsonDeserializer<?> findEnumDeserializer(final Class<?> type, final Deser
                 for (AnnotatedMethod am : factoryMethods) {
                     final JsonCreator creator = am.getAnnotation(JsonCreator.class);
                     if (creator != null) {
-                        return EnumDeserializer.deserializerForCreator(config, type, am, null, null);
+                        return EnumDeserializer.deserializerForCreator(
+                            config, type, am, null, null, null);
                     }
                 }
             }

src/test/java/com/fasterxml/jackson/databind/deser/enums/EnumDeserializationTest.java

@@ -161,7 +161,7 @@ static enum EnumWithDefaultAnnoAndConstructor {
     }
 
     static enum StrictEnumCreator {
-        A, B;
+        A, B, @JsonEnumDefaultValue UNKNOWN;
 
         @JsonCreator public static StrictEnumCreator fromId(String value) {
             for (StrictEnumCreator e: values()) {
@@ -453,7 +453,7 @@ public void testAllowUnknownEnumValuesReadAsNull() throws Exception
         assertNull(reader.forType(TestEnum.class).readValue(" 4343 "));
     }
 
-    // Ability to ignore unknown Enum values:
+    // Ability to ignore unknown Enum values as null:
 
     // [databind#1642]
     @Test
@@ -483,6 +483,19 @@ public void testAllowUnknownEnumValuesAsMapKeysReadAsNull() throws Exception
         assertTrue(result.map.containsKey(null));
     }
 
+    // Ability to ignore unknown Enum values as a defined default:
+
+    // [databind#4979]
+    @Test
+    public void testAllowUnknownEnumValuesReadAsDefaultWithCreatorMethod4979(() throws Exception
+    {
+        ObjectReader reader = MAPPER.reader(
+            DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE);
+        assertEquals(
+            StrictEnumCreator.UNKNOWN,
+            reader.forType(StrictEnumCreator.class).readValue("\"NO-SUCH-VALUE\""));
+    }
+
     @Test
     public void testDoNotAllowUnknownEnumValuesAsMapKeysWhenReadAsNullDisabled() throws Exception
     {