tidying string to char conversion

org.springframework.core/src/main/java/org/springframework/core/convert/support/StringToCharacterConverter.java

@@ -30,6 +30,9 @@ class StringToCharacterConverter implements Converter<String, Character> {
 		if ("".equals(source)) {
 			return null;
 		}
+		if (source.length() > 1) {
+			throw new IllegalArgumentException("Can only convert a [String] with length of 1 to a [Character]; string value '" + source + "'  has length of " + source.length());
+		}
 		return source.charAt(0);
 	}