Fix onDuplicateKey.

Author: orekyuu

doma-core/src/main/java/org/seasar/doma/jdbc/criteria/statement/EntityqlMultiInsertStatement.java

@@ -42,7 +42,7 @@ public EntityqlMultiInsertStatement(
    *
    * @return statement
    */
-  public EntityqlMultiInsertStatement<ENTITY> onDuplicateKeyUpdate() {
+  public Statement<MultiResult<ENTITY>> onDuplicateKeyUpdate() {
     this.duplicateKeyType = DuplicateKeyType.UPDATE;
     return this;
   }
@@ -52,7 +52,7 @@ public EntityqlMultiInsertStatement<ENTITY> onDuplicateKeyUpdate() {
    *
    * @return statement
    */
-  public EntityqlMultiInsertStatement<ENTITY> onDuplicateKeyIgnore() {
+  public Statement<MultiResult<ENTITY>> onDuplicateKeyIgnore() {
     this.duplicateKeyType = DuplicateKeyType.IGNORE;
     return this;
   }