Use box-impl function as factory for kotlin value class

Author: wplong11

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

@@ -277,10 +277,19 @@ private List<AnnotatedMethod> _findPotentialFactories(TypeFactory typeFactory,
 
     private static boolean _isIncludableFactoryMethod(Method m)
     {
-        return Modifier.isStatic(m.getModifiers())
-                // 09-Nov-2020, ckozak: Avoid considering synthetic methods such as
-                // lambdas used within methods because they're not relevant.
-                && !m.isSynthetic();
+        if (!Modifier.isStatic(m.getModifiers())) {
+            return false;
+        }
+
+        boolean isSynthetic = m.isSynthetic();
+        boolean kotlinValueClassFactory = isSynthetic && m.getName().equals("box-impl");
+        if (kotlinValueClassFactory) {
+            return true;
+        }
+
+        // 09-Nov-2020, ckozak: Avoid considering synthetic methods such as
+        // lambdas used within methods because they're not relevant.
+        return !isSynthetic;
     }
 
     protected AnnotatedConstructor constructDefaultConstructor(ClassUtil.Ctor ctor,