Properties should be now in UTF-8

[pdemanget]

Since java 9, properties should be in UTF-8 unless specifically configured else:
https://docs.oracle.com/javase/9/intl/internationalization-enhancements-jdk-9.htm#JSINT-GUID-974CF488-23E8-4963-A322-82006A7A14C7

The properties Loader still user ISO hardcoded, see this file:
https://github.com/spring-projects/spring-boot/blob/main/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/env/OriginTrackedPropertiesLoader.java

        CharacterReader(Resource resource) throws IOException {
		this.reader = new LineNumberReader(
				new InputStreamReader(resource.getInputStream(), StandardCharsets.ISO_8859_1));
	}

Would it be possible to use UTF_8 be default?
It would still be configurable sith the environment var
java.util.PropertyResourceBundle.encoding=ISO-8859-1

[wilkinsona]

The change in JDK 9 is specifically for properties-based resource bundles used for internationalization. General loading of properties is not affected and continues to use ISO-8859-1.

#28663 is tracking a configuration option for this or, possibly, a change to Boot's default.