Fixed the issue of type loss in generalized call cases. (#15562)

Author: wuwen5

dubbo-common/src/main/java/org/apache/dubbo/common/utils/PojoUtils.java

@@ -160,7 +160,7 @@ private static Object generalize(Object pojo, Map<Object, Object> history) {
         }
 
         if (pojo instanceof LocalDate || pojo instanceof LocalDateTime || pojo instanceof LocalTime) {
-            return pojo.toString();
+            return pojo;
         }
 
         if (pojo instanceof Class) {

dubbo-common/src/test/java/org/apache/dubbo/common/utils/PojoUtilsTest.java

@@ -772,15 +772,15 @@ void testJava8Time() {
 
         Object localDateTimeGen = PojoUtils.generalize(LocalDateTime.now());
         Object localDateTime = PojoUtils.realize(localDateTimeGen, LocalDateTime.class);
-        assertEquals(localDateTimeGen, localDateTime.toString());
+        assertEquals(localDateTimeGen, localDateTime);
 
         Object localDateGen = PojoUtils.generalize(LocalDate.now());
         Object localDate = PojoUtils.realize(localDateGen, LocalDate.class);
-        assertEquals(localDateGen, localDate.toString());
+        assertEquals(localDateGen, localDate);
 
         Object localTimeGen = PojoUtils.generalize(LocalTime.now());
         Object localTime = PojoUtils.realize(localTimeGen, LocalTime.class);
-        assertEquals(localTimeGen, localTime.toString());
+        assertEquals(localTimeGen, localTime);
     }
 
     @Test