Provide a way to access Gradle module metadata files from dependency resolution

[ljacomet]

There is currently a way, through ArtifactResolutionQuery, to get at the POM files for a dependency resolution result.
Gradle should offer a similar access to the Gradle Module Metadata file.

While it might make sense to offer access to metadata through the ResolvableDependencies in the future, this does not mean a more direct / custom access is not needed for specific use cases.

[jjohannes]

Closing this as the use case can be addressed with component metadata rules:

gradle/subprojects/dependency-management/src/integTest/groovy/org/gradle/integtests/resolve/rules/VariantFilesMetadataRulesIntegrationTest.groovy

Lines 87 to 114 in fd9eb88

	class DirectMetadataAccessVariantRule implements ComponentMetadataRule {
	@javax.inject.Inject
	ObjectFactory getObjects() { }
	void execute(ComponentMetadataContext context) {
	def id = context.details.id
	context.details.maybeAddVariant("apiElementsWithMetadata", "api") {
	attributes {
	attribute(Category.CATEGORY_ATTRIBUTE, objects.named(Category, Category.DOCUMENTATION))
	attribute(DocsType.DOCS_TYPE_ATTRIBUTE, objects.named(DocsType, "all-files"))
	}
	withFiles {
	addFile("\${id.name}-\${id.version}.pom")
	addFile("\${id.name}-\${id.version}.module")
	}
	}
	context.details.maybeAddVariant("compileWithMetadata", "compile") {
	attributes {
	attribute(Category.CATEGORY_ATTRIBUTE, objects.named(Category, Category.DOCUMENTATION))
	attribute(DocsType.DOCS_TYPE_ATTRIBUTE, objects.named(DocsType, "all-files"))
	}
	withFiles {
	addFile("\${id.name}-\${id.version}.pom")
	}
	}
	}
	}

(improved by #11565 in 6.1)