Allow to configure the version file encoding

[Vampire]

Without this setting, the JVM default encoding is used. This can easily break files if they contain non-ASCII characters. A properties file for example by definintion is ISO-8859-1 encoded. Java 18+ use UTF-8 as default encoding if nothing else is configured. If you now manipulate the version file using UTF-8, it gets crippled if it contains non-ASCII characters.
With this new setting the encoding can be configured, with the appropriate default setting according to the default for the file.

[Copilot]

Pull request overview

This PR introduces a configurable encoding property for version property files to prevent corruption of non-ASCII characters when using Java 18+ (which defaults to UTF-8 encoding). The new versionPropertyFileEncoding property defaults to 'ISO-8859-1', the standard encoding for Java properties files.

Key Changes:

• Added versionPropertyFileEncoding property to ReleaseExtension with ISO-8859-1 as the default
• Updated all file read and write operations to use the configured encoding
• Documented the new configuration option in README

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
ReleaseExtension.groovy	Adds new versionPropertyFileEncoding property with ISO-8859-1 default
UnSnapshotVersion.groovy	Updates properties file reading to use configured encoding
PrepareVersions.groovy	Updates version writing to pass encoding parameter
BaseReleaseTask.groovy	Updates writeVersion method signature and calls to use encoding parameter
PluginHelper.groovy	Updates writeVersion method signature and all calls to use encoding parameter
README.md	Documents the new configuration option with default value

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Hillkorn]

I thought java uses the encoding that is configured in the system via env variables for example but falls back to the ISO default in case there is nothing configured. If someone would have that configured we might break their files I guess?!?
Maybe gradle does it different here but I'm not 100% sure if this change doesn't beak existing projects.

[Vampire]

Ah, sorry, missed your question.

I thought java uses the encoding that is configured in the system via env variables for example but falls back to the ISO default in case there is nothing configured. If someone would have that configured we might break their files I guess?!?
Maybe gradle does it different here but I'm not 100% sure if this change doesn't beak existing projects.

Java uses the default encoding.
In older Java versions this is depending on the System encoding, so on most western european Windows systems it will by Cp1252, on most eastern european Windows systems it is another one, on most *nix systems it is UTF-8.
But even those are not guaranteed.

In newer Java versions the default changed to always be UTF-8 to fix that mess you always get by just running somewhere different and it suddenly behaves totally different.

WIth Gradle in specific it additionally depends on how you run Gradle iirc.
If you for example run the CLI with Java 8 but the daemon runs on Java 21, still the CLI Java version dictates the default encoding afair.

The encoding of a .properties file like gradle.properties though is defined by the format specification to be ISO-8859-1 always, except if you forcefully set an encoding when parsing and writing the file.
But the standard encoding is ISO-8859-1 and not the system default encoding whatever it is.

Also if you use some other file as version file, it most probably should also not follow the system encoding but have a fixedly defined encoding to not behave differently depending on where it is read.

In the - imho - quite unlikely case that someone for example has a gradle.properties file that is encoded in non ISO-8859-1, they can still configure the encoding then with this PR merged. But for the normal case there is currently no way to make the plugin behave properly, except for making sure the file only contains ASCII characters.

[Vampire]

Btw.: