Provide explicit support for Groovy source code

Status Quo

Groovy source code files are not officially supported by Spotless.

You therefore have to hack something together like the following:

format 'groovy', {
    target '**/*.groovy'
    indentWithTabs()
    trimTrailingWhitespace()
    endWithNewline()
    licenseHeaderFile rootProject.file('src/spotless/eclipse-public-license-1.0.java'), "package "

    customReplaceRegex 'class-level Javadoc indentation fix', /^\*/, ' *'
    customReplaceRegex 'nested Javadoc indentation fix', /\t\*/, '\t *'
}

Without the custom regular expressions, Spotless will mangle Javadoc and license header comment blocks.

Proposal

• Support Groovy scripts as a first-class citizen with built-in support for license headers and Javadoc comment blocks.

[fvgh]

Hi. I am unfortunately also not a groovy expert. Actually I just wanted to know more about gradle, so I also had a look at Groovy. When I started to write my first dummy plugins, I searched for a better way to format code automatically (still used ANT…), so I found spotless and try to learn from its source how to write gradle plugins. Since I found the p2.asmaven provided by @nedtwigg fascinating, I started to write a formatter step using the GrEclipse plugin. Anyhow, I am cleaning up my prove-of-concept and committing it step by step to my fork. Maybe (with some help 😉 ) I can manage to push it to a usable state within a few week(end)s.

[nedtwigg]

Travis is working again.