Simplify implementation of internal VariableNotAvailableException

Since VariableNotAvailableException is not a public type, there is no
need to store the variable name in a field/property.

spring-context/src/main/java/org/springframework/cache/interceptor/CacheEvaluationContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -25,12 +25,12 @@ import org.springframework.core.ParameterNameDiscoverer;
 import org.springframework.lang.Nullable;
 
 /**
- * Cache specific evaluation context that adds a method parameters as SpEL
- * variables, in a lazy manner. The lazy nature eliminates unneeded
- * parsing of classes byte code for parameter discovery.
+ * Cache-specific evaluation context that adds method parameters as SpEL
+ * variables, in a lazy manner. The lazy nature avoids unnecessary
+ * parsing of a class's byte code for parameter discovery.
  *
- * <p>Also define a set of "unavailable variables" (i.e. variables that should
- * lead to an exception right the way when they are accessed). This can be useful
+ * <p>Also defines a set of "unavailable variables" (i.e. variables that should
+ * lead to an exception as soon as they are accessed). This can be useful
  * to verify a condition does not match even when not all potential variables
  * are present.
  *
@@ -55,10 +55,10 @@ class CacheEvaluationContext extends MethodBasedEvaluationContext {
 
 
 	/**
-	 * Add the specified variable name as unavailable for that context.
-	 * Any expression trying to access this variable should lead to an exception.
-	 * <p>This permits the validation of expressions that could potentially a
-	 * variable even when such variable isn't available yet. Any expression
+	 * Add the specified variable name as unavailable for this context.
+	 * <p>Any expression trying to access this variable should lead to an exception.
+	 * <p>This permits the validation of expressions that could potentially access
+	 * a variable even when such a variable isn't available yet. Any expression
 	 * trying to use that variable should therefore fail to evaluate.
 	 */
 	public void addUnavailableVariable(String name) {

spring-context/src/main/java/org/springframework/cache/interceptor/VariableNotAvailableException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -19,8 +19,8 @@ package org.springframework.cache.interceptor;
 import org.springframework.expression.EvaluationException;
 
 /**
- * A specific {@link EvaluationException} to mention that a given variable
- * used in the expression is not available in the context.
+ * An internal {@link EvaluationException} which signals that a given variable
+ * used in an expression is not available in the context.
  *
  * @author Stephane Nicoll
  * @since 4.0.6
@@ -28,17 +28,8 @@ import org.springframework.expression.EvaluationException;
 @SuppressWarnings("serial")
 class VariableNotAvailableException extends EvaluationException {
 
-	private final String name;
-
-
 	public VariableNotAvailableException(String name) {
-		super("Variable not available");
-		this.name = name;
-	}
-
-
-	public final String getName() {
-		return this.name;
+		super("Variable '" + name + "' not available");
 	}
 
 }

spring-context/src/test/java/org/springframework/cache/interceptor/CacheOperationExpressionEvaluatorTests.java

@@ -43,12 +43,14 @@ import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 
 /**
+ * Tests for {@link CacheOperationExpressionEvaluator}.
+ *
  * @author Costin Leau
  * @author Phillip Webb
  * @author Sam Brannen
  * @author Stephane Nicoll
  */
-class ExpressionEvaluatorTests {
+class CacheOperationExpressionEvaluatorTests {
 
 	private final StandardEvaluationContext originalEvaluationContext = new StandardEvaluationContext();
 
@@ -125,9 +127,9 @@ class ExpressionEvaluatorTests {
 	@Test
 	void unavailableReturnValue() {
 		EvaluationContext context = createEvaluationContext(CacheOperationExpressionEvaluator.RESULT_UNAVAILABLE);
-		assertThatExceptionOfType(VariableNotAvailableException.class).isThrownBy(() ->
-				new SpelExpressionParser().parseExpression("#result").getValue(context))
-			.satisfies(ex -> assertThat(ex.getName()).isEqualTo("result"));
+		assertThatExceptionOfType(VariableNotAvailableException.class)
+			.isThrownBy(() -> new SpelExpressionParser().parseExpression("#result").getValue(context))
+			.withMessage("Variable 'result' not available");
 	}
 
 	@Test