bugfix: jackson serializing can compatible with empty beans

Author: haibojiang

trpc-core/src/main/java/com/tencent/trpc/core/utils/JsonUtils.java

@@ -16,6 +16,7 @@
 import com.fasterxml.jackson.databind.DeserializationFeature;
 import com.fasterxml.jackson.databind.JavaType;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.SerializationFeature;
 import com.tencent.trpc.core.exception.ErrorCode;
 import com.tencent.trpc.core.exception.TRpcException;
 import com.tencent.trpc.core.logger.Logger;
@@ -39,6 +40,8 @@ public class JsonUtils {
         objectMapper.setSerializationInclusion(Include.NON_NULL);
         // Do not throw an error when deserializing if there are no corresponding properties
         objectMapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
+        // Do not throw an error when serializing if there are no public fields
+        objectMapper.disable(SerializationFeature.FAIL_ON_EMPTY_BEANS);
     }
 
     /**

trpc-core/src/test/java/com/tencent/trpc/core/utils/JsonUtilsTest.java

@@ -32,6 +32,7 @@ public class JsonUtilsTest {
     private static final String JSON = "{\"test\":123}";
     private static final String JSON_LIST = "[{\"test\":123},{\"test\":123}]";
     private static final String ERROR_JSON = "{\"test\":123,A}";
+    private static final String EMPTY_JSON = "{}";
 
     @Test
     public void testCopy() {
@@ -184,6 +185,12 @@ public void testConvertValue() {
     }
 
 
+    @Test
+    public void testEmptyBeanSerial() {
+        TestEmptyBean testEmptyBean = new TestEmptyBean(10);
+        Assert.assertEquals(EMPTY_JSON, JsonUtils.toJson(testEmptyBean));
+    }
+
     public static class TestObj {
 
         private int testA;
@@ -232,4 +239,14 @@ public void setData(String data) {
             this.data = data;
         }
     }
+
+    public static class TestEmptyBean {
+
+        // without public getter method
+        private int field;
+
+        public TestEmptyBean(int field) {
+            this.field = field;
+        }
+    }
 }