MethodReference.MethodValueRef.setValue throws SpelEvaluationException

Closes gh-22336

spring-expression/src/main/java/org/springframework/expression/spel/ast/MethodReference.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.
@@ -395,7 +395,7 @@ public class MethodReference extends SpelNodeImpl {
 
 		@Override
 		public void setValue(@Nullable Object newValue) {
-			throw new IllegalAccessError();
+			throw new SpelEvaluationException(0, SpelMessage.NOT_ASSIGNABLE, MethodReference.this.name);
 		}
 
 		@Override