MessageSource.getMessage returns null default message as-is (again)

Issue: SPR-16127

spring-context/src/main/java/org/springframework/context/MessageSource.java

@@ -53,6 +53,7 @@ public interface MessageSource {
 	 * otherwise the default message passed as a parameter
 	 * @see java.text.MessageFormat
 	 */
+	@Nullable
 	String getMessage(String code, @Nullable Object[] args, @Nullable String defaultMessage, Locale locale);
 
 	/**

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

@@ -143,8 +143,7 @@ public abstract class AbstractMessageSource extends MessageSourceSupport impleme
 			return msg;
 		}
 		if (defaultMessage == null) {
-			String fallback = getDefaultMessage(code);
-			return (fallback != null ? fallback : "");
+			return getDefaultMessage(code);
 		}
 		return renderDefaultMessage(defaultMessage, args, locale);
 	}
@@ -264,8 +263,7 @@ public abstract class AbstractMessageSource extends MessageSourceSupport impleme
 			else {
 				// Check parent MessageSource, returning null if not found there.
 				// Covers custom MessageSource impls and DelegatingMessageSource.
-				String msg = parent.getMessage(code, args, null, locale);
-				return ("".equals(msg) ? null : msg);
+				return parent.getMessage(code, args, null, locale);
 			}
 		}
 		// Not found in parent either.

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

@@ -54,6 +54,7 @@ public class DelegatingMessageSource extends MessageSourceSupport implements Hie
 
 
 	@Override
+	@Nullable
 	public String getMessage(String code, @Nullable Object[] args, @Nullable String defaultMessage, Locale locale) {
 		if (this.parentMessageSource != null) {
 			return this.parentMessageSource.getMessage(code, args, defaultMessage, locale);
@@ -62,7 +63,7 @@ public class DelegatingMessageSource extends MessageSourceSupport implements Hie
 			return renderDefaultMessage(defaultMessage, args, locale);
 		}
 		else {
-			return "";
+			return null;
 		}
 	}
 

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

@@ -84,7 +84,8 @@ public class MessageSourceAccessor {
 	 * @return the message
 	 */
 	public String getMessage(String code, String defaultMessage) {
-		return this.messageSource.getMessage(code, null, defaultMessage, getDefaultLocale());
+		String msg = this.messageSource.getMessage(code, null, defaultMessage, getDefaultLocale());
+		return (msg != null ? msg : "");
 	}
 
 	/**
@@ -95,7 +96,8 @@ public class MessageSourceAccessor {
 	 * @return the message
 	 */
 	public String getMessage(String code, String defaultMessage, Locale locale) {
-		return this.messageSource.getMessage(code, null, defaultMessage, locale);
+		String msg = this.messageSource.getMessage(code, null, defaultMessage, locale);
+		return (msg != null ? msg : "");
 	}
 
 	/**
@@ -106,7 +108,8 @@ public class MessageSourceAccessor {
 	 * @return the message
 	 */
 	public String getMessage(String code, @Nullable Object[] args, String defaultMessage) {
-		return this.messageSource.getMessage(code, args, defaultMessage, getDefaultLocale());
+		String msg = this.messageSource.getMessage(code, args, defaultMessage, getDefaultLocale());
+		return (msg != null ? msg : "");
 	}
 
 	/**
@@ -118,7 +121,8 @@ public class MessageSourceAccessor {
 	 * @return the message
 	 */
 	public String getMessage(String code, @Nullable Object[] args, String defaultMessage, Locale locale) {
-		return this.messageSource.getMessage(code, args, defaultMessage, locale);
+		String msg = this.messageSource.getMessage(code, args, defaultMessage, locale);
+		return (msg != null ? msg : "");
 	}
 
 	/**

spring-context/src/test/java/org/springframework/context/support/ResourceBundleMessageSourceTests.java

@@ -162,6 +162,7 @@ public class ResourceBundleMessageSourceTests {
 		assertEquals("Hello, message1", ac.getMessage("hello", args, Locale.ENGLISH));
 
 		// test default message without and with args
+		assertNull(ac.getMessage(null, null, null, Locale.ENGLISH));
 		assertEquals("default", ac.getMessage(null, null, "default", Locale.ENGLISH));
 		assertEquals("default", ac.getMessage(null, args, "default", Locale.ENGLISH));
 		assertEquals("{0}, default", ac.getMessage(null, null, "{0}, default", Locale.ENGLISH));

spring-webflux/src/main/java/org/springframework/web/reactive/result/view/RequestContext.java

@@ -282,6 +282,9 @@ public class RequestContext {
 	 */
 	public String getMessage(String code, @Nullable Object[] args, String defaultMessage, boolean htmlEscape) {
 		String msg = this.messageSource.getMessage(code, args, defaultMessage, this.locale);
+		if (msg == null) {
+			return "";
+		}
 		return (htmlEscape ? HtmlUtils.htmlEscape(msg) : msg);
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/support/RequestContext.java

@@ -653,6 +653,9 @@ public class RequestContext {
 	 */
 	public String getMessage(String code, @Nullable Object[] args, String defaultMessage, boolean htmlEscape) {
 		String msg = this.webApplicationContext.getMessage(code, args, defaultMessage, getLocale());
+		if (msg == null) {
+			return "";
+		}
 		return (htmlEscape ? HtmlUtils.htmlEscape(msg) : msg);
 	}
 
@@ -732,7 +735,8 @@ public class RequestContext {
 	 * @return the message
 	 */
 	public String getThemeMessage(String code, String defaultMessage) {
-		return getTheme().getMessageSource().getMessage(code, null, defaultMessage, getLocale());
+		String msg = getTheme().getMessageSource().getMessage(code, null, defaultMessage, getLocale());
+		return (msg != null ? msg : "");
 	}
 
 	/**
@@ -745,7 +749,8 @@ public class RequestContext {
 	 * @return the message
 	 */
 	public String getThemeMessage(String code, @Nullable Object[] args, String defaultMessage) {
-		return getTheme().getMessageSource().getMessage(code, args, defaultMessage, getLocale());
+		String msg = getTheme().getMessageSource().getMessage(code, args, defaultMessage, getLocale());
+		return (msg != null ? msg : "");
 	}
 
 	/**
@@ -758,8 +763,9 @@ public class RequestContext {
 	 * @return the message
 	 */
 	public String getThemeMessage(String code, @Nullable List<?> args, String defaultMessage) {
-		return getTheme().getMessageSource().getMessage(code, (args != null ? args.toArray() : null),
+		String msg = getTheme().getMessageSource().getMessage(code, (args != null ? args.toArray() : null),
 				defaultMessage, getLocale());
+		return (msg != null ? msg : "");
 	}
 
 	/**

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/MessageTag.java

@@ -300,6 +300,7 @@ public class MessageTag extends HtmlEscapingAwareTag implements ArgumentAware {
 		this.arguments = null;
 	}
 
+
 	/**
 	 * Resolve the specified message into a concrete message String.
 	 * The returned message String should be unescaped.
@@ -322,8 +323,9 @@ public class MessageTag extends HtmlEscapingAwareTag implements ArgumentAware {
 
 			if (this.text != null) {
 				// We have a fallback text to consider.
-				return messageSource.getMessage(
+				String msg = messageSource.getMessage(
 						this.code, argumentsArray, this.text, getRequestContext().getLocale());
+				return (msg != null ? msg : "");
 			}
 			else {
 				// We have no fallback text to consider.