Add a failing test for #1604

src/test/java/com/fasterxml/jackson/failing/NestedTypes1604Test.java

@@ -0,0 +1,84 @@
+package com.fasterxml.jackson.failing;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import com.fasterxml.jackson.databind.*;
+
+// for [databind#1604]
+public class NestedTypes1604Test extends BaseMapTest
+{
+    public static class Data<T> {
+        private T data;
+
+        public Data(T data) {
+             this.data = data;
+        }
+
+        public T getData() {
+             return data;
+        }
+
+        public static <T> Data<List<T>> of(List<T> data) {
+             return new DataList<>(data);
+        }
+    }
+
+    public static class DataList<T> extends Data<List<T>> {
+        public DataList(List<T> data) {
+            super(data);
+        }
+    }
+
+    public static class Inner {
+        private int index;
+
+        public Inner(int index) {
+             this.index = index;
+        }
+
+        public int getIndex() {
+             return index;
+        }
+    }
+
+    public static class BadOuter {
+        private Data<List<Inner>> inner;
+
+        public BadOuter(Data<List<Inner>> inner) {
+            this.inner = inner;
+        }
+
+        public Data<List<Inner>> getInner() {
+            return inner;
+        }
+    }
+
+    public static class GoodOuter {
+        private DataList<Inner> inner;
+
+        public GoodOuter(DataList<Inner> inner) {
+            this.inner = inner;
+        }
+
+        public DataList<Inner> getInner() {
+            return inner;
+        }
+    }
+
+    public void testIssue1604() throws Exception
+    {
+        final ObjectMapper objectMapper = newObjectMapper();
+        List<Inner> inners = new ArrayList<>();
+        for (int i = 0; i < 2; i++) {
+            inners.add(new Inner(i));
+        }
+        BadOuter badOuter = new BadOuter(Data.of(inners));
+        GoodOuter goodOuter = new GoodOuter(new DataList<>(inners));
+//        String json = objectMapper.writeValueAsString(goodOuter);
+
+        // 11-Oct-2017, tatu: Fails with exception wrt type specialization
+        String json = objectMapper.writeValueAsString(badOuter);
+        assertNotNull(json);
+   }
+}