ISO8859-1 properties files get changed into UTF-8 when filtered

Create:

src/main/resources/test.properties

And add a ISO8859-1 character that is not ASCII or UTF-8, do not use \uXXXX formatting.

When adding this line:

<resource><directory>src/main/resources</directory><filtering>true</filtering></resource>

Expected:

ISO8859-1 encoded file in jar.

Actual:

UTF-8 encoded file in jar.

—

If there are any property files (which can only be ISO8859-1) they appear to be converted into UTF-8 in the jar.