Generate hashcode on the java types.

editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/TypeHierarchyItem.java

Index: editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/TypeHierarchyItem.java
diff --git a/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/TypeHierarchyItem.java b/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/TypeHierarchyItem.java
index 839767970287003ce1c6748f3e0c17fb45d49128..c6659959e4aad10d3af8da0b980dfae0cdb6869f 100644
--- a/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/TypeHierarchyItem.java
+++ b/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/TypeHierarchyItem.java
@@ -26,6 +26,7 @@ import com.google.gson.JsonArray;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 import com.google.gson.JsonPrimitive;
+import org.apache.commons.lang3.builder.HashCodeBuilder;
 import java.util.ArrayList;
 import java.util.Iterator;
 import org.apache.commons.lang3.StringUtils;
@@ -194,6 +195,19 @@ public class TypeHierarchyItem {
     return superclass;
   }
 
+  @Override
+  public int hashCode() {
+    HashCodeBuilder builder = new HashCodeBuilder();
+    builder.append(classElement);
+    builder.append(displayName);
+    builder.append(memberElement);
+    builder.append(superclass);
+    builder.append(interfaces);
+    builder.append(mixins);
+    builder.append(subclasses);
+    return builder.toHashCode();
+  }
+
   public JsonObject toJson() {
     JsonObject jsonObject = new JsonObject();
     jsonObject.add("classElement", classElement.toJson());