Added tests to ensure that subclass objects that are of a parameterized type are serialized per their declared type in lists or maps.

gson/src/test/java/com/google/gson/functional/MoreSpecificTypeSerializationTest.java

@@ -70,6 +70,49 @@ public class MoreSpecificTypeSerializationTest extends TestCase {
     assertEquals(3, sub.get("s").getAsInt());
   }
 
+  /**
+   * For parameterized type, Gson ignores the more-specific type and sticks to the declared type
+   */
+  public void testParameterizedSubclassFields() {
+    ClassWithParameterizedBaseFields target = new ClassWithParameterizedBaseFields(
+        new ParameterizedSub<String>("one", "two"));
+    String json = gson.toJson(target);
+    assertTrue(json.contains("\"t\":\"one\""));
+    assertFalse(json.contains("\"s\""));
+  }
+
+  /**
+   * For parameterized type in a List, Gson ignores the more-specific type and sticks to
+   * the declared type
+   */
+  public void testListOfParameterizedSubclassFields() {
+    Collection<ParameterizedBase<String>> list = new ArrayList<ParameterizedBase<String>>();
+    list.add(new ParameterizedBase<String>("one"));
+    list.add(new ParameterizedSub<String>("two", "three"));
+    ClassWithContainersOfParameterizedBaseFields target =
+      new ClassWithContainersOfParameterizedBaseFields(list, null);
+    String json = gson.toJson(target);
+    assertTrue(json, json.contains("{\"t\":\"one\"}"));
+    assertFalse(json, json.contains("\"s\":"));
+  }
+
+  /**
+   * For parameterized type in a map, Gson ignores the more-specific type and sticks to the
+   * declared type
+   */
+  public void testMapOfParameterizedSubclassFields() {
+    Map<String, ParameterizedBase<String>> map = new HashMap<String, ParameterizedBase<String>>();
+    map.put("base", new ParameterizedBase<String>("one"));
+    map.put("sub", new ParameterizedSub<String>("two", "three"));
+    ClassWithContainersOfParameterizedBaseFields target =
+      new ClassWithContainersOfParameterizedBaseFields(null, map);
+    JsonObject json = gson.toJsonTree(target).getAsJsonObject().get("map").getAsJsonObject();
+    assertEquals("one", json.get("base").getAsJsonObject().get("t").getAsString());
+    JsonObject sub = json.get("sub").getAsJsonObject();
+    assertEquals("two", sub.get("t").getAsString());
+    assertNull(sub.get("s"));
+  }
+
   private static class Base {
     int b;
     Base(int b) {
@@ -100,4 +143,36 @@ public class MoreSpecificTypeSerializationTest extends TestCase {
       this.map = map;
     }
   }
+
+  private static class ParameterizedBase<T> {
+    T t;
+    ParameterizedBase(T t) {
+      this.t = t;
+    }
+  }
+
+  private static class ParameterizedSub<T> extends ParameterizedBase<T> {
+    T s;
+    ParameterizedSub(T t, T s) {
+      super(t);
+      this.s = s;
+    }
+  }
+
+  private static class ClassWithParameterizedBaseFields {
+    ParameterizedBase<String> b;
+    ClassWithParameterizedBaseFields(ParameterizedBase<String> b) {
+      this.b = b;
+    }
+  }
+
+  private static class ClassWithContainersOfParameterizedBaseFields {
+    Collection<ParameterizedBase<String>> collection;
+    Map<String, ParameterizedBase<String>> map;
+    ClassWithContainersOfParameterizedBaseFields(Collection<ParameterizedBase<String>> collection,
+        Map<String, ParameterizedBase<String>> map) {
+      this.collection = collection;
+      this.map = map;
+    }
+  }
 }