fix code

hutool-json/src/test/java/cn/hutool/json/Issue2447Test.java

@@ -0,0 +1,29 @@
+package cn.hutool.json;
+
+import lombok.Data;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.time.LocalDateTime;
+
+public class Issue2447Test {
+
+	@Test
+	public void addIntegerTest() {
+		Time time = new Time();
+		time.setTime(LocalDateTime.of(1970, 1, 2, 10, 0, 1, 0));
+		String timeStr = JSONUtil.toJsonStr(time);
+		Assert.assertEquals(timeStr, "{\"time\":93601000}");
+		Assert.assertEquals(JSONUtil.toBean(timeStr, Time.class).getTime(), time.getTime());
+	}
+
+	@Data
+	static class Time {
+		private LocalDateTime time;
+
+		@Override
+		public String toString() {
+			return time.toString();
+		}
+	}
+}