Polishing

spring-context/src/main/java/org/springframework/context/support/StaticMessageSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,6 +43,7 @@ public class StaticMessageSource extends AbstractMessageSource {
 
 
 	@Override
+	@Nullable
 	protected String resolveCodeWithoutArguments(String code, Locale locale) {
 		return this.messages.get(code + '_' + locale.toString());
 	}