fix flaky test deserializeDateTimeProperty

Author: xinying7

modules/swagger-core/src/test/java/io/swagger/v3/core/serialization/properties/PropertySerializationTest.java

@@ -77,12 +77,15 @@ public void serializeDateTimeProperty() throws IOException {
 
     @Test(description = "it should deserialize a DateTimeProperty")
     public void deserializeDateTimeProperty() throws IOException {
-        final String json = "{\"type\":\"string\",\"format\":\"date-time\"}";
-        final Schema p = m.readValue(json, Schema.class);
+        final String json1 = "{\"type\":\"string\",\"format\":\"date-time\"}";
+        final Schema p = m.readValue(json1, Schema.class);
         assertEquals(p.getType(), "string");
         assertEquals(p.getFormat(), "date-time");
         assertEquals(p.getClass(), DateTimeSchema.class);
-        assertEquals(m.writeValueAsString(p), json);
+        String json2 = m.writeValueAsString(p);
+        JSONObject jsonObj1 = new JSONObject(json1);
+        JSONObject jsonObj2 = new JSONObject(json2);
+        JSONAssert.assertEquals(jsonObj1, jsonObj2, true);
     }
 
     @Test(description = "it should serialize a DoubleProperty")