- [x] I have searched the [issues](https://github.com/apache/dubbo/issues) of this repository and believe that this is not a duplicate.
- [x] I have checked the [FAQ](https://github.com/apache/dubbo/blob/master/FAQ.md) of this repository and believe that this is not a duplicate.

### Environment

* Dubbo version: 2.7.2
* Operating System version: OSX
* Java version: 1.8

### Steps to reproduce this issue

```java
@Test
public void testSerializeSqlDate() throws IOException, ClassNotFoundException {
    java.sql.Date originTime = new java.sql.Date(System.currentTimeMillis());
    this.protostuffObjectOutput.writeObject(originTime);
    this.flushToInput();

    java.sql.Date serializedTime = protostuffObjectInput.readObject(java.sql.Date.class);
    assertThat(serializedTime, is(originTime));
}
```
### Expected Result

What do you expected from the above steps？

### Actual Result

```shell
Expected: is <2019-06-25>
   but: was <1970-01-01>
Expected :is <2019-06-25>
  Actual   :<1970-01-01>
```

If there is an exception, please attach the exception trace:

```
```

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
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 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.dubbo.common.serialize.protostuff;
import static org.hamcrest.CoreMatchers.is;
import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.nullValue;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.sql.Timestamp;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
public class ProtostuffObjectOutputTest {