refactor: convert FileContentsTask to Java

[baptistemesta]

Relates to #34459

#34459

[baptistemesta]

I was not sure about test naming conventions.
I only added some unit tests since the task is pretty straightforward.

[elasticmachine]

Pinging @elastic/es-core-infra

[alpar-t]

Thanks for your contribution @baptistemesta !
This looks good, just left a few comments.

[alpar-t]

We prefer adding the set prefix.

Suggested change

	public void contents(Object contents) {
	public void setContents(Object contents) {

Also in this particular case I think we should also make a semantic change and type contents with String. This does mean that groovy will resolve GStrings sooner, but looking at the uses of this task that is ok and I would prefer the stronger typing, it's one of the reasons we convert in the first place.
We can always lather add a version that takes Supplier<String> if we need it to be more dynamic.

[alpar-t]

Suggested change

	public void file(Object file) {
	public void setFile(File file) {
	this.file = file;
	}
	public void setFile(String file) {
	this.file = getProject().file(file);
	}

Along the same lines as above to avoid the use of Object.

[alpar-t]

I would prefer we use something like Files.write where we can be specific about the encoding.
FileWriter will rely on the default encoding, something we generally try to avoid.

[alpar-t]

@elasticmachine test this please

[baptistemesta]

I integrated changes.

• When using setFile and setContents, the configuration closure needs to use = I think
• Change the task to have strongly typed methods

I have an issue with the Files.writeString, build fails with:

> Task :build-tools:compileJava FAILED
/Users/baptiste/git/elasticsearch/buildSrc/src/main/java/org/elasticsearch/gradle/FileContentsTask.java:62: error: cannot find symbol
        Files.writeString(file.toPath(), contents, Charset.forName("UTF-8"));
             ^
  symbol:   method writeString(Path,String,Charset)
  location: class Files
1 error

[alpar-t]

I have an issue with the Files.writeString, build fails with:

The method is Files.write, it takes byte[] as argument.
You control the encoding when converting from string to byte[]

[alpar-t]

The equals is ok, other parts of the build use it as well and I think it's the direction Gradle is going into w.r.t. task properties.
We could do without the as File if we have a setFile(String file) method, see my previous suggestion.

[alpar-t]

@elasticmachine test this please

[alpar-t]

Please use getProject().file() here to be consistent with how Gradle resolves strings to files.
For relative paths, new File() is relative to the current working directory, while project.file() is relative to project.projectDir.

[alpar-t]

@elasticmachine test this please

[baptistemesta]

Yep I was using Files.writeString which exists since java 11...
all is integrated I think

[alpar-t]

Looks good, will wait for CI and merge if all goes well.
Thanks again for your contribution!
One last time, @elasticmachine test this please.

[alpar-t]

@elasticmachine test this please

[alpar-t]

@baptistemesta please look at the CI failures. Checkstyle found some unused imports.

@elasticmachine run packaging tests

[alpar-t]

@elasticmachine run sample packaging tests

[baptistemesta]

@atorok Ok i'll fix that, thanks

[baptistemesta]

all good, fixed codestyle + squashed all commits

[alpar-t]

@elasticmachine test this please

[alpar-t]

@baptistemesta While not immediately obvious, the packaging-sample failure is most likely related to your PR. The other one does not seem like it, try merging master in.
@elasticmachine ok to test

[alpar-t]

@baptistemesta I'm closing this due to lack of activity, please reopen if you plan to work on it,