Remove unnecessary boxing

Closes gh-1817

spring-expression/src/main/java/org/springframework/expression/spel/standard/Tokenizer.java

 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -265,7 +265,7 @@ class Tokenizer {
 						raiseParseException(this.pos, SpelMessage.UNEXPECTED_ESCAPE_CHAR);
 						break;
 					default:
-						throw new IllegalStateException("Cannot handle (" + Integer.valueOf(ch) + ") '" + ch + "'");
+						throw new IllegalStateException("Cannot handle ('" + ch + "')");
 				}
 			}
 		}