Apply license header to `package-info.java` and `module-info.java`

[jacek99]

We added spotless with the Google Java style:

spotless {
    java {
        googleJavaFormat("1.7")
        licenseHeaderFile "${project.rootDir}/company.license.java"
    }
}

and it formatted all code...but left all the package-info.java classes untouched when we run spotlessJavaApply

is that expected behaviour or a bug? How can we force the format to include those files as well?

[nedtwigg]

I believe google-java-format is applied to these files, it's only the license header step which is not.

spotless/plugin-gradle/src/main/java/com/diffplug/gradle/spotless/JavaExtension.java

Lines 191 to 193 in 45d2122

	if (LicenseHeaderStep.name().equals(step.getName())) {
	return step.filterByFile(LicenseHeaderStep.unsupportedJvmFilesFilter());
	} else {

spotless/lib/src/main/java/com/diffplug/spotless/generic/LicenseHeaderStep.java

Lines 39 to 40 in 45d2122

	private static final SerializableFileFilter UNSUPPORTED_JVM_FILES_FILTER = SerializableFileFilter.skipFilesNamed(
	"package-info.java", "package-info.groovy", "module-info.java");

In order to fix this, we would need a smarter delimiter for detecting the start of these files:

spotless/plugin-gradle/src/main/java/com/diffplug/gradle/spotless/JavaExtension.java

Lines 47 to 49 in 45d2122

	// If this constant changes, don't forget to change the similarly-named one in
	// testlib/src/test/java/com/diffplug/spotless/generic/LicenseHeaderStepTest.java as well
	static final String LICENSE_HEADER_DELIMITER = "package ";

The trick is that we'll need a different delimiter depending on what the filename is. This is possible, but most of our steps are filename-agnostic.

Workaround

You can do something like this (untested):

spotless {
    java {
        googleJavaFormat("1.7")
        licenseHeaderFile "${project.rootDir}/company.license.java"
    }
    format 'javaMisc', {
        target 'src/**/package-info.java', 'src/**/module-info.java'
        licenseHeaderFile "${project.rootDir}/company.license.java", 'some-delimiter-i-dont-know-what'
    }
}

[jbduncan]

I'm actually not sure if google-java-format has any specific support for package-info.java and module-info.java files.

A quick search on GitHub suggests that it doesn't crash when formatting module-info.java files and perhaps package-info.java ones as well, but not necessarily that they're formatted neatly or at all, which your experience seems to confirm.

Thus I'd suggest that you keep an eye here for module-info.java support. As for package-info.java support, I'm not entirely sure...

@nedtwigg I admit I fail to see how your example above would allow (package|module)-info.java files to be formatted with google-java-format. Would you mind clarifying for me?

[nedtwigg]

I fail to see how your example above would allow (package|module)-info.java files to be formatted with google-java-format.

Most of our users don't realize that the "steps" are independent - it feels like they're configuring one step. -info.java files have very little java content - their most noticeable part is their javadoc / license header.

In @jacek99's original example, google-java-format is already being applied to -info.java files, and it's easy to miss that your single "package blah;" declaration had some whitespace trimmed by google-java-format, when what you expected was a license header.

That's why I focused this issue to say "Spotless does delegate out to your formatter, but it is a known limitation that the license header part will not happen, this is why, and this is how you can fix it or work around it".

[jbduncan]

In @jacek99's original example, google-java-format is already being applied to -info.java files, and it's easy to miss that your single "package blah;" declaration had some whitespace trimmed by google-java-format, when what you expected was a license header.

Ahh, okay, I'd completely misunderstood what was happening here; I thought the problem was that google-java-format wasn't being applied to those files by default!

Thanks for clarifying @nedtwigg. :)

[alvarosanchez]

Just to confirm that @nedtwigg's workaround works simply by using package as delimiter:

spotless {
    java {
        ...
    }
    format 'javaMisc', {
        target 'src/**/package-info.java', 'src/**/module-info.java'
        licenseHeaderFile rootProject.file('config/spotless.license.java'), 'package '
    }
}

[alvarosanchez]

Actually I take that back. It does apply the license, but also remove the Javadoc

[alvarosanchez]

Using '\\/\\*\\*' as delimiter seems to do the trick, but I guess it won't work with packages without Javadoc

[nedtwigg]

As best we could tell, there wasn’t a single regex that worked for all cases, you need a full Java parser, which is why it has gone unsupported so long.