add UnitTest about MessageConvert

infra/common/src/test/java/cn/hippo4j/common/toolkit/MessageConvertTest.java

@@ -33,6 +33,12 @@ import java.util.*;
  */
 public class MessageConvertTest {
 
+    @Test
+    public void TestMessageConvert(){
+        MessageConvert messageConvert = new MessageConvert();
+        Assertions.assertNotNull(messageConvert);
+    }
+
     @Test
     public void testConvert() {
         AbstractMessage message = new RuntimeMessage();