Polish "Add support for custom expression parsing"

See gh-27604

spring-context/src/main/java/org/springframework/context/expression/CachedExpressionEvaluator.java

@@ -75,7 +75,7 @@ protected ParameterNameDiscoverer getParameterNameDiscoverer() {
 
 	/**
 	 * Return the {@link Expression} for the specified SpEL value
-	 * <p>Parse the expression if it hasn't been already.
+	 * <p>{@link #parseExpression(String) Parse the expression} if it hasn't been already.
 	 * @param cache the cache to use
 	 * @param elementKey the element on which the expression is defined
 	 * @param expression the expression to parse
@@ -92,18 +92,20 @@ protected Expression getExpression(Map<ExpressionKey, Expression> cache,
 		return expr;
 	}
 
-	private ExpressionKey createKey(AnnotatedElementKey elementKey, String expression) {
-		return new ExpressionKey(elementKey, expression);
-	}
-
 	/**
-	 * Parse the expression
+	 * Parse the specified {@code expression}.
 	 * @param expression the expression to parse
+	 * @since 5.3.13
 	 */
 	protected Expression parseExpression(String expression) {
 		return getParser().parseExpression(expression);
 	}
 
+	private ExpressionKey createKey(AnnotatedElementKey elementKey, String expression) {
+		return new ExpressionKey(elementKey, expression);
+	}
+
+
 	/**
 	 * An expression key.
 	 */

spring-context/src/test/java/org/springframework/context/expression/CachedExpressionEvaluatorTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 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.