Write Properties files in a reproducible way

[Zlika]

Java does not write java.util.Properties files in a reproducible way: there is a timestamp, the order of the lines is not reproducible, and the new line character used is system-dependent.
This PR fixes this problem by removing the timestamp, ordering the lines in the alphabetical order and using a system-independent new line character.
This is a follow-up of #4546 and #4569.

[github-actions]

Test Results

  606 files  ±0    606 suites  ±0   4h 21m 55s ⏱️ + 4m 38s
  434 tests ±0    422 ✅  - 3   7 💤 ±0  0 ❌  - 2  5 🔥 +5 
1 302 runs  ±0  1 274 ✅  - 4  22 💤 ±0  0 ❌  - 2  6 🔥 +6 

For more details on these errors, see this check.

Results for commit 74067e9. ± Comparison against base commit e052363.

This pull request removes 1 and adds 1 tests. Note that renamed tests count towards both.

org.eclipse.tycho.test.reproducible.ReproducibleBuildTest ‑ test

org.eclipse.tycho.test.reproducible.ReproducibleBuildTest ‑ testReproducible

♻️ This comment has been updated with latest results.

[laeubi]

and the new line character used is system-dependent.

Last time I followed a discussion with the maven folks, they said that newlines are always a problem for reproducible build and one should rebuild on the same system architecture, so maybe not a big deal but probably also don't harm much.

[Zlika]

and the new line character used is system-dependent.

Last time I followed a discussion with the maven folks, they said that newlines are always a problem for reproducible build and one should rebuild on the same system architecture, so maybe not a big deal but probably also don't harm much.

That's true, but when maven-archiver fixes the pom.properties file (in https://github.com/apache/maven-archiver/blob/master/src/main/java/org/apache/maven/shared/archiver/PomPropertiesUtil.java) it also uses a system-independent newline character. Anyway, trying to reuse the existing newline characters would make the code more complex, so it's simpler to use a system-independent newline character here. It would be dangerous to try to blindly fix all the text files to use a system-independent newline character, but when we need to rewrite a file it makes sens to take the opportunity to do it.

[Zlika]

Hi @laeubi, I took into account all your remarks. Thanks.

[merks]

Perhaps the same conclusion as in eclipse-equinox/p2#589 (comment) applies here, i.e., with Java 21 the properties are sorted and you can set a fixed reproducible timestamp via java.properties.date...

[Zlika]

Perhaps the same conclusion as in eclipse-equinox/p2#589 (comment) applies here, i.e., with Java 21 the properties are sorted and you can set a fixed reproducible timestamp via java.properties.date...

Using a system property to set the date is quite messy, but it's an interesting workaround when tycho calls external tools like p2. It's a pity that this feature was only added in Java 18.

[laeubi]

@Zlika can you adjust the util method to use Path API then I think this can be merged so we have also the support for java 21 at laest in the core Tycho.

[Zlika]

@Zlika can you adjust the util method to use Path API then I think this can be merged so we have also the support for java 21 at laest in the core Tycho.

Done.

[laeubi]

Just a few adjustments and I think we are done!

[laeubi]

This all looks fine and consistent to me now.

[eclipse-tycho-bot]

💚 All backports created successfully

Status	Branch	Result
✅	tycho-4.0.x

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