Fix #5115: @JsonUnwrapped deserialization can't handle name collision

src/main/java/tools/jackson/databind/introspect/POJOPropertiesCollector.java

@@ -1056,21 +1056,28 @@ private void _addCreatorParams(Map<String, POJOPropertyBuilder> props,
             final boolean hasExplicit = (explName != null);
             final POJOPropertyBuilder prop;
 
-            //  neither implicit nor explicit name?
-            if (!hasExplicit && (implName == null)) {
-                boolean isUnwrapping = _annotationIntrospector.findUnwrappingNameTransformer(_config, param) != null;
-
-                if (isUnwrapping) {
-                    // If unwrapping, can use regardless of name; we will use a placeholder name
-                    // anyway to try to avoid name conflicts.
+            // [databind#5115] Resolve @JsonUnwrapped by checking the parameter first, then falling back to its field.
+            final String implNameStr = (implName != null) ? implName.getSimpleName() : null;
+            final POJOPropertyBuilder existingProp = (implNameStr != null) ? props.get(implNameStr) : null;
+            final AnnotatedField field = (existingProp != null) ? existingProp.getField() : null;
+
+            // [databind#5115] Determine whether the creator parameter should be treated as unwrapped.
+            final boolean isUnwrapping =
+                _annotationIntrospector.findUnwrappingNameTransformer(_config, param) != null ||
+                    (field != null && _annotationIntrospector.findUnwrappingNameTransformer(_config, field) != null);
+
+            if (isUnwrapping) {
+                // [databind#5115] Serialization: Reuse the existing property, Deserialization: Use a placeholder creator property
+                if (_forSerialization && existingProp != null) {
+                    existingProp.addCtor(param, implName, hasExplicit, true, false);
+                    prop = existingProp;
+                } else {
                     PropertyName name = UnwrappedPropertyHandler.creatorParamName(param.getIndex());
                     prop = _property(props, name);
-                    prop.addCtor(param, name, false, true, false);
-                } else {
-                    // Without name, cannot make use of this creator parameter -- may or may not
-                    // be a problem, verified at a later point.
-                    prop = null;
+                    prop.addCtor(param, name, hasExplicit, true, false);
                 }
+            } else if (!hasExplicit && (implName == null)) {
+                prop = null;
             } else {
                 // 27-Dec-2019, tatu: [databind#2527] may need to rename according to field
                 if (implName != null) {

src/test/java/tools/jackson/databind/records/tofix/RecordUnwrapped5115Test.java → src/test/java/tools/jackson/databind/records/RecordUnwrapped5115Test.java

@@ -1,11 +1,10 @@
-package tools.jackson.databind.records.tofix;
+package tools.jackson.databind.records;
 
 import org.junit.jupiter.api.Test;
 
 import com.fasterxml.jackson.annotation.JsonUnwrapped;
 import tools.jackson.databind.ObjectMapper;
 import tools.jackson.databind.testutil.DatabindTestUtil;
-import tools.jackson.databind.testutil.failure.JacksonTestFailureExpected;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
@@ -62,7 +61,6 @@ void unwrappedRecordShouldRoundTripPass() throws Exception
         assertEquals(input, output);
     }
 
-    @JacksonTestFailureExpected
     @Test
     void unwrappedRecordShouldRoundTrip() throws Exception
     {