Fix #3601

Author: cowtowncoder

release-notes/VERSION

@@ -54,5 +54,6 @@ Versions: 3.x (for earlier see VERSION-2.x)
 #3047: Rename `Bean[De]SerializerModifier` as `Value[De]SerializerModifier`
 #3536: Create new exception type `JsonNodeException` for use by `JsonNode`-related problems
 #3542: Rename "com.fasterxml.jackson" -> "tools.jackson"
+#3601: Change `Optional` deserialization from "absent" value into `null`, from "empty"
 - Remove `MappingJsonFactory`
 - Add context parameter for `TypeSerializer` contextualization (`forProperty()`)

src/main/java/tools/jackson/databind/ext/jdk8/Jdk8OptionalDeserializer.java

@@ -42,6 +42,16 @@ public Object getEmptyValue(DeserializationContext ctxt) {
         return getNullValue(ctxt);
     }
 
+    /**
+     * Let's actually NOT coerce missing Creator parameters into empty value.
+     */
+    @Override
+    public Object getAbsentValue(DeserializationContext ctxt) {
+        // 21-Sep-2022, tatu: [databind#3601] Let's make absent become `null`,
+        //   NOT "null value" (Empty)
+        return null;
+    }
+
     @Override
     public Optional<?> referenceValue(Object contents) {
         return Optional.ofNullable(contents);

src/test/java/tools/jackson/databind/ext/jdk8/CreatorForOptionalTest.java

@@ -40,9 +40,11 @@ public void testCreatorWithOptional() throws Exception
                 a2q("{'a':'foo'}"), CreatorWithOptionalStrings.class);
         assertNotNull(bean);
         assertNotNull(bean.a);
-        assertNotNull(bean.b);
         assertTrue(bean.a.isPresent());
-        assertFalse(bean.b.isPresent());
-        assertEquals("foo", bean.a.get());
+
+        // 21-Sep-2022, tatu: [databind#3601] Changed this to now become proper
+        //    `null`. Should probably also check coercion in future.
+        
+        assertNull(bean.b);
     }
 }