Fix build failures

Author: rstoyanchev

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/ResponseBodyResultHandlerTests.java

@@ -149,7 +149,8 @@ private void testProblemDetailMediaType(MockServerWebExchange exchange, MediaTyp
 						"\"title\":\"Bad Request\"," +
 						"\"status\":400," +
 						"\"detail\":null," +
-						"\"instance\":\"/path\"}");
+						"\"instance\":\"/path\"," +
+						"\"properties\":null}");
 	}
 
 	@Test

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/ResponseEntityResultHandlerTests.java

@@ -260,7 +260,8 @@ public void handleErrorResponse() {
 						"\"title\":\"Bad Request\"," +
 						"\"status\":400," +
 						"\"detail\":null," +
-						"\"instance\":\"/path\"}");
+						"\"instance\":\"/path\"," +
+						"\"properties\":null}");
 	}
 
 	@Test
@@ -280,7 +281,8 @@ public void handleProblemDetail() {
 						"\"title\":\"Bad Request\"," +
 						"\"status\":400," +
 						"\"detail\":null," +
-						"\"instance\":\"/path\"}");
+						"\"instance\":\"/path\"," +
+						"\"properties\":null}");
 	}
 
 	@Test