Model interface exposes getAttribute method (next to add/contains)

Fixes gh-22145

Author: jhoeller

spring-context/src/main/java/org/springframework/ui/ConcurrentModel.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.
@@ -161,6 +161,12 @@ public boolean containsAttribute(String attributeName) {
 		return containsKey(attributeName);
 	}
 
+	@Override
+	@Nullable
+	public Object getAttribute(String attributeName) {
+		return get(attributeName);
+	}
+
 	@Override
 	public Map<String, Object> asMap() {
 		return this;

spring-context/src/main/java/org/springframework/ui/Model.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.
@@ -76,6 +76,15 @@ public interface Model {
 	 */
 	boolean containsAttribute(String attributeName);
 
+	/**
+	 * Return the attribute value for the given name, if any.
+	 * @param attributeName the name of the model attribute (never {@code null})
+	 * @return the corresponding attribute value, or {@code null} if none
+	 * @since 5.2
+	 */
+	@Nullable
+	Object getAttribute(String attributeName);
+
 	/**
 	 * Return the current set of model attributes as a Map.
 	 */

spring-context/src/main/java/org/springframework/ui/ModelMap.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.
@@ -144,4 +144,15 @@ public boolean containsAttribute(String attributeName) {
 		return containsKey(attributeName);
 	}
 
+	/**
+	 * Return the attribute value for the given name, if any.
+	 * @param attributeName the name of the model attribute (never {@code null})
+	 * @return the corresponding attribute value, or {@code null} if none
+	 * @since 5.2
+	 */
+	@Nullable
+	public Object getAttribute(String attributeName) {
+		return get(attributeName);
+	}
+
 }