Add missing @Override annotations

spring-web/src/test/java/org/springframework/http/converter/json/MappingJackson2HttpMessageConverterTests.java

@@ -455,10 +455,12 @@ public class MappingJackson2HttpMessageConverterTests {
 
 		private String string;
 
+		@Override
 		public String getString() {
 			return string;
 		}
 
+		@Override
 		public void setString(String string) {
 			this.string = string;
 		}

spring-web/src/test/java/org/springframework/http/converter/json/SpringHandlerInstantiatorTests.java

@@ -228,6 +228,7 @@ public class SpringHandlerInstantiatorTests {
 		}
 
 		// New in Jackson 2.7
+		@Override
 		public String getDescForKnownTypeIds() {
 			return null;
 		}