Use ELContext instead of VariableResolver in JspPropertyAccessor

The JSP VariableResolver API has been deprecated since JSP 2.1 in favor
of the newer ELContext API.

This commit therefore refactors JspPropertyAccessor to use the
ELContext API.

Closes gh-32383

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/EvalTag.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.
@@ -18,6 +18,7 @@ package org.springframework.web.servlet.tags;
 
 import java.io.IOException;
 
+import jakarta.el.ELContext;
 import jakarta.servlet.jsp.JspException;
 import jakarta.servlet.jsp.PageContext;
 
@@ -96,6 +97,7 @@ import org.springframework.web.util.TagUtils;
  *
  * @author Keith Donald
  * @author Juergen Hoeller
+ * @author Sam Brannen
  * @since 3.0.1
  */
 @SuppressWarnings("serial")
@@ -212,11 +214,12 @@ public class EvalTag extends HtmlEscapingAwareTag {
 		private final PageContext pageContext;
 
 		@Nullable
-		private final jakarta.servlet.jsp.el.VariableResolver variableResolver;
+		private final ELContext elContext;
+
 
 		public JspPropertyAccessor(PageContext pageContext) {
 			this.pageContext = pageContext;
-			this.variableResolver = pageContext.getVariableResolver();
+			this.elContext = pageContext.getELContext();
 		}
 
 		@Override
@@ -252,11 +255,11 @@ public class EvalTag extends HtmlEscapingAwareTag {
 
 		@Nullable
 		private Object resolveImplicitVariable(String name) throws AccessException {
-			if (this.variableResolver == null) {
+			if (this.elContext == null) {
 				return null;
 			}
 			try {
-				return this.variableResolver.resolveVariable(name);
+				return this.elContext.getELResolver().getValue(this.elContext, name, null);
 			}
 			catch (Exception ex) {
 				throw new AccessException(