Spring boot gradle plugin default encoding

[rwinch]

This commit converts SpringBootPlugin into a Groovy based plugin (to ease the UTF-8 default encoding) and adds default UTF-8 encoding. The reasoning for this is based upon spring-guides/gs-spring-boot#7

[wilkinsona]

I'm not convinced of the need to convert SpringBootPlugin to Groovy just to make this change. This, I believe, is the same change but in Java:

project.getTasks().withType(Compile.class).all(new Action<Compile>() {
    @Override
    public void execute(Compile compileTask) {
        if (!StringUtils.hasText(compileTask.getOptions().getEncoding())) {
            compileTask.getOptions().setEncoding("UTF-8");
        }
    }
});

[rwinch]

@wilkinsona That is true, but why aren't we using Groovy is the better question? It makes the PR much cleaner, it is much more concise, simple, etc.... Are you not in favor of using Groovy or just that it should be distinct PR / Commit?

[wilkinsona]

I'm not sure of the reasons behind not using Groovy for the plugin. I think it was @philwebb who took the original decision. If we're going to move the plugin to Groovy, I think it'd be better done as a separate piece of work. I'd also expect us to convert most if not all of the code to Groovy as part of that change.

[dsyer]

Agree that it's a separate topic. The reason we don't use groovy is probably because of the pain involved in building groovy projects with Maven (which is not a justification for migrating to gradle, by the way). But it looks like we already have groovy code in there, so I see no reason not to merge this.

[philwebb]

There was no real logic behind not using Groovy other than the rest of the project was pure Java. Many many parts of the Gradle plugin could probably be improved if we switched.