Fix #2091

Author: cowtowncoder

release-notes/CREDITS-2.x

@@ -1110,3 +1110,7 @@ Robin Roos (robinroos@github)
 Mike Gilbode (gilbode@github)
   * Reported #792: Deserialization Not Working Right with Generic Types and Builders
   (2.12.0)
+
+Nate Bauernfeind (nbauernfeind@github)
+  * Reported #2091: `ReferenceType` does not expose valid containedType
+  (2.12.0)

release-notes/VERSION-2.x

@@ -8,6 +8,8 @@ Project: jackson-databind
 
 #792: Deserialization Not Working Right with Generic Types and Builders
  (reported by Mike G; fix contributed by Ville K)
+#2091: `ReferenceType` does not expose valid containedType
+ (reported by Nate B)
 #2683: Explicitly fail (de)serialization of `java.time.*` types in absence of
   registered custom (de)serializers
 #2707: Improve description included in by `DeserializationContext.handleUnexpectedToken()`

src/main/java/com/fasterxml/jackson/databind/type/TypeFactory.java

@@ -957,7 +957,8 @@ public JavaType constructSimpleType(Class<?> rawType, Class<?> parameterTarget,
      */
     public JavaType constructReferenceType(Class<?> rawType, JavaType referredType)
     {
-        return ReferenceType.construct(rawType, null, // no bindings
+        return ReferenceType.construct(rawType,
+                TypeBindings.create(rawType, referredType), // [databind#2091]
                 null, null, // or super-class, interfaces?
                 referredType);
     }

src/test/java/com/fasterxml/jackson/databind/type/TestJavaType.java

@@ -280,7 +280,12 @@ public void testConstructReferenceType() throws Exception
         assertTrue(t.hasContentType());
         assertEquals(Long.class, t.getContentType().getRawClass());
 
-        // 26-Mar-2020, tatu: [databind#2019] suggest this should be 1...
-//        assertEquals(1, t.containedTypeCount());
+        // 26-Mar-2020, tatu: [databind#2019] made this work
+        assertEquals(1, t.containedTypeCount());
+        TypeBindings bindings = t.getBindings();
+        assertEquals(1, bindings.size());
+        assertEquals(refdType, bindings.getBoundType(0));
+        // Should we even verify this or not?
+        assertEquals("V", bindings.getBoundName(0));
     }
 }