CompanionObject.kt

companion object {
    const val PMD_FILE_NAME = "pmd-ruleset.xml"
    const val CHECKSTYLE_FILE_NAME = "checkstyle.xml"
    const val FINDBUGS_FILE_NAME = "findbugs-exclude.xml"
    const val WRITE_PMD_CONFIG_FILE_TASK = "writePmdConfigFile"
    const val WRITE_CHECK_STYLE_CONFIG_FILE_TASK = "writeCheckStyleConfigFile"
    const val WRITE_FIND_BUGS_EXCLUSION_FILE_TASK = "writeFindBugsExclusionFile"
    const val VERIFICATION_GROUP = "verification"
    const val PLUGIN_EXTENSION_NAME = "qualityChecks"
}

KotlinJUnitTest.kt

    @Test
    fun `plugin should add tasks when applied`() {
        with(project) {
            pluginManager.apply(QualityChecksPlugin::class.java)

            assertNotNull(tasks.findByName(WRITE_CHECK_STYLE_CONFIG_FILE_TASK))
            assertNotNull(tasks.findByName(WRITE_FIND_BUGS_EXCLUSION_FILE_TASK))
            assertNotNull(tasks.findByName(WRITE_PMD_CONFIG_FILE_TASK))
        }
    }

QualityChecksExtension.groovy

class QualityChecksExtension {
    String pmdConfigFile = 'quality-checks/pmd-ruleset.xml'
    String checkstyleConfigFile = 'quality-checks/checkstyle.xml'
    String findBugsExclusionFile  = 'quality-checks/findbugs-exclude.xml'
}

QualityChecksExtension.kt

import info.adavis.qualitychecks.QualityChecksPlugin.Companion.CHECKSTYLE_FILE_NAME
import info.adavis.qualitychecks.QualityChecksPlugin.Companion.FINDBUGS_FILE_NAME
import info.adavis.qualitychecks.QualityChecksPlugin.Companion.PMD_FILE_NAME

open class QualityChecksExtension(var pmdConfigFile: String = "quality-checks/$PMD_FILE_NAME",
                                  var checkstyleConfigFile: String = "quality-checks/$CHECKSTYLE_FILE_NAME",
                                  var findBugsExclusionFile: String = "quality-checks/$FINDBUGS_FILE_NAME")