Gradle: fix creation of wrapper

[jburel]

When creating the wrapper in the current directory, gradle already tries to build with the version currently installed (5.6.1).
I only discovered the problem when working on omero-blitz.
When this is merged, we can update the gradle.yml file in the various repositories or wait for the publication steps
to be included.

Tested changes on all ubuntu, windows and mac: https://github.com/jburel/omero-model/actions/runs/411333070

[sbesson]

@jburel i have not seen the error but have you tried moving the action checking out the repository after the ones setting up the Java environment including Gradle?

[jburel]

you will still need to move gradlew to the folder where the code is checked out in order to work so it is not going to really simplify things

[jburel]

The error is the following

A problem occurred evaluating root project 'omero-blitz'.
> Could not create task ':generateObjectFactoryRegistrarPsql'.
   > Could not create task of type 'FileGeneratorTask'.
      > Please use the ObjectFactory.mapProperty() method to create a property of type Map<K, V>.

cf. https://github.com/jburel/omero-blitz/runs/1525813901

This is an error that occurs with gradle 6.x. That error also means that the build.gradle is checked.

[jburel]

I did some test using my current PR of omero-blitz see https://github.com/jburel/omero-blitz/actions/runs/412338740
running the - uses: actions/checkout@v2 after the rest.
If we use the current directory as the place to wrap, the content is then deleted during the checkout phase, so unless we move gradlew to another folder like /tmp, it is not going to work i.e. it is not going to be much simpler that the solution suggested in this PR

[sbesson]

Understood, thanks for the error I was able to reproduce locally. So the issue is not about building than simply evaluating the root project which is indeed incompatible with Gradle 6.x for omero-blitz. It's unfortunate there is not built-in way to install the specified version before evaluating the project.

Looking at ome/omero-blitz#113, the omero-blitz is already itself an extension of this template as it requires extra dependencies installed. Apart from omero-blitz, how many repositories require a version of Gradle that differs from the default?

[sbesson]

In case the default installed version of Gradle is used, is this custom installation necessary?

[jburel]

it is otherwise we cannot use gradlew in the following step

[sbesson]

I failed to find a failing build in these circumstances as it looks like all the omero-* workflows are overriding gradle_version.

[jburel]

omero-blitz is the only one so far, so we could keep the template as it is
and aim at adjusting the code to use a more recent version of gradle. Gradle 7 is out so, I think we should work on the code to allow an upgrade

[sbesson]

Understood, if omero-blitz is the only one, I would also be inclined to keep this workflow as generic as possible and create an an issue to review and upgrade omero-blitz build.gradle and make it compatible with Gradle 6.x or 7.x depending on the target.

In case it's useful, while reviewing wrapper, I also discovered https://docs.gradle.org/current/dsl/org.gradle.api.tasks.wrapper.Wrapper.html#org.gradle.api.tasks.wrapper.Wrapper:gradleVersion. This won't help solving this particular issue but could help reducing the number of variables maintained in the workflow by pushing down the Gradle version to the configuration file.

[jburel]

It is still generic with the change proposed in this PR. It makes sure it works.

[jburel]

That strategy no longer works with Gradle7!