org.jetbrains.changelog.Changelog.Item.plus doesn't keep withHeader and other boolean flags

[rybak]

Describe the bug
I'm trying to add additional list items to <change-notes> in the Gradle task patchPluginXml of Gradle IntelliJ Plugin. I'm trying to modify output of the Changelog Plugin. Unfortunately, function org.jetbrains.changelog.Changelog.Item.plus loses the value of withHeader and other boolean flags, which were set up in the call chain before plus() is invoked.

Below is a minimal example that doesn't require Gradle IntelliJ Plugin.

To Reproduce
This is code, slightly modified from IntelliJ Platform Plugin Template. Two methods withHeader and withEmptySections are used as an example – these are just the two boolean flags that I've checked, others are probably affected in the same way.

1. Put the following code at the top level of the build.gradle.kts, for simplicity:

with(project.changelog) {
	val extraItems = mapOf(
		"Extra section" to setOf("[Extra link](https://example.org)")
	)
	println(renderItem(
		getUnreleased()
			.withHeader(false)
			.withEmptySections(true)
			.plus(Changelog.Item("", "", "", false, extraItems, "", "")),
		Changelog.OutputType.MARKDOWN
	))
}

2. Put the following Markdown text in CHANGELOG.md:

# Changelog

## [Unreleased]

### Added
- Example added item, "Changed" is empty

### Changed

## [0.2.0-alpha]

[Unreleased]: https://github.com/rybak/intellij-copy-commit-reference/compare/v0.2.0-alpha...HEAD
[0.2.0-alpha]: https://github.com/rybak/intellij-copy-commit-reference/compare/v0.1.0-alpha.1...v0.2.0-alpha

3. Run ./gradlew

Actual behavior
Header ## [Unreleased] is printed in the log, empty section is absent:

## [Unreleased]

### Added
- Example added item, "Changed" is empty

### Extra section
- [Extra link](https://example.org)

[Unreleased]: https://github.com/rybak/intellij-copy-commit-reference/compare/v0.2.0-alpha...HEAD

Expected behavior
Header is not printed in the log, empty section is present:

### Added
- Example added item, "Changed" is empty

### Changed

### Extra section
- [Extra link](https://example.org)

[Unreleased]: https://github.com/rybak/intellij-copy-commit-reference/compare/v0.2.0-alpha...HEAD

Environment:

• Gradle Changelog Plugin Version 2.1.0
• Gradle Version 8.1.1

Additional context

• Workaround – call with* functions after the plus function:

with(project.changelog) {
	val extraItems = mapOf(
		"Extra section" to setOf("[Extra link](https://example.org)")
	)
	println(renderItem(
		getUnreleased()
			.plus(Changelog.Item("", "", "", false, extraItems, "", ""))
			.withHeader(false)
			.withEmptySections(true),
		Changelog.OutputType.MARKDOWN
	))
}

• I'm not yet familiar with how copy() works in Kotlin, but this bug has something to do with the fact that function plus() is not calling private fun copy. Instead, the constructor, which sets the default values for affected flags is invoked.

[hsz]

Thanks for reporting, @rybak!
Indeed, an incorrect copy was picked. Fixed with this workaround: 992281e