Update release notes wrt #2895

Author: cowtowncoder

release-notes/CREDITS-2.x

@@ -808,6 +808,9 @@ Jakub Skierbiszewski (jskierbi@github)
 Carter Kozak (cakofony@github)
   * Reported #2016: Delegating JsonCreator disregards JsonDeserialize info
    (2.9.6)
+  * Contributed #2895: Improve static factory method generic type resolution logic
+    (as well as better test coverage)
+   (2.12.0)
 
 Reinhard Prechtl (dnno@github)
   * Reported #2034: Serialization problem with type specialization of nested generic types

release-notes/VERSION-2.x

@@ -26,6 +26,8 @@ Project: jackson-databind
 #2885: Add `JsonNode.canConvertToExactIntegral()` to indicate whether floating-point/BigDecimal
   values could be converted to integers losslessly
  (requested by Oguzhan U; implementation contributed by Siavash S)
+#2895: Improve static factory method generic type resolution logic
+ (contributed by Carter K)
 #2903: Allow preventing "Enum from integer" coercion using new `CoercionConfig` system
 #2909: `@JsonValue` not considered when evaluating inclusion
  (reported by chrylis@github)

src/main/java/com/fasterxml/jackson/databind/introspect/AnnotatedCreatorCollector.java

@@ -258,12 +258,13 @@ private List<AnnotatedMethod> _findPotentialFactories(TypeFactory typeFactory,
             AnnotatedMethod factory = result.get(i);
             if (factory == null) {
                 Method candidate = candidates.get(i);
-                // Apply generic type information based on the requested type
+                // 06-Nov-2020, tatu: Fix from [databind#2895] will try to resolve
+                //   nominal static method type bindings into expected target type
+                //   (if generic types involved)
                 TypeResolutionContext typeResCtxt = MethodGenericTypeResolver.narrowMethodTypeParameters(
                         candidate, type, typeFactory, emptyTypeResCtxt);
                 result.set(i,
-                        constructFactoryCreator(candidate,
-                                typeResCtxt, null));
+                        constructFactoryCreator(candidate, typeResCtxt, null));
             }
         }
         return result;

src/main/java/com/fasterxml/jackson/databind/introspect/MethodGenericTypeResolver.java

@@ -13,11 +13,15 @@
 import java.util.Objects;
 
 /**
- * Internal utility functionality to handle type resolution for method type variables based on the requested
- * result type.
+ * Internal utility functionality to handle type resolution for method type variables
+ * based on the requested result type: this is needed to work around the problem of
+ * static factory methods not being able to use class type variable bindings
+ * (see [databind#2895] for more).
+ *
+ * @since 2.12
  */
-final class MethodGenericTypeResolver {
-
+final class MethodGenericTypeResolver
+{
     /*
      * Attempt to narrow types on a generic factory method based on the expected result (requestedType).
      * If narrowing was possible, a new TypeResolutionContext is returned with the discovered TypeBindings,
@@ -30,7 +34,7 @@ final class MethodGenericTypeResolver {
      * as though the method was written with defined types:
      * @JsonCreator static Wrapper<Duck> fromJson(Duck value)
      */
-    static TypeResolutionContext narrowMethodTypeParameters(
+    public static TypeResolutionContext narrowMethodTypeParameters(
             Method candidate,
             JavaType requestedType,
             TypeFactory typeFactory,
@@ -214,8 +218,4 @@ private static TypeVariable<?> findByName(TypeVariable<?>[] typeVariables, Strin
         }
         return null;
     }
-
-    private MethodGenericTypeResolver() {
-        // Utility class
-    }
 }