Gradle update: 3.5.1

[jubeira]

Upgrading Gradle version to 3.5.1.

[gb96]

I tried applying this PR in the indigo branch and it works fine.

I also went a step further and tried latest Gradle version 4.6. That also seems to work fine.

Is there a reason to prefer 3.5.1 over 4.6 for this project?

Actually I think Gradle 4.6 works okay with Java 9, but Gradle 3.5.1 is broken for Java 9. This would be a good reason to upgrade to Gradle 4.6

[gb96]

See also rosjava_build_tools/pull/35

[jubeira]

Hi @gb96,

I think you may try that, but I had a problem when using Gradle 4.x on Android projects. It's actually an annoying detail: Gradle 4.x uses Android plugin 3.x, which needs Android Build tools 26+. This version of the build tools removed the android command from the SDK, which is used by the command line tools to create projects (see https://github.com/rosjava/rosjava_build_tools/issues/31).

I would prefer to keep all the projects with the same Gradle version. Do you need Java 9? IMHO, I would:

• Update to Gradle 3.5.1, which is already an improvement
• Try to fix command line tools for Android (i.e. don't depend on android command which was removed)
• Upgradle Gradle to 4.x

[gb96]

Hi @jubeira I understand the Android/Gradle issues much better now, thanks. My project is not Android so Gradle 4.6 and Java 9 work well for me.

[ernestmc]

lgtm