travis.gradle

import groovy.json.JsonBuilder

def packageDir = "${GROUP.replace('.', '/')}/${ARTIFACT_ID}"

task writeDescriptor {
    def builder = new JsonBuilder()
    def root = builder {
        'package' {
            name ARTIFACT_ID
            repo 'maven'
            subject BINTRAY_SUBJECT
            desc POM_DESCRIPTION
            website_url POM_URL
            issue_tracker_url ISSUE_URL
            vcs_url GIT_URL
            github_use_tag_release_notes true
            github_release_notes_file 'README.md'
            licenses POM_LICENCE_NAME
//            labels 'labels'
            public_download_numbers true
        }
        'version' {
            name VERSION_CODE
            desc POM_DESCRIPTION
            released new Date().format('yyyy-MM-dd')
            vcs_tag VERSION_CODE
            gpgSign true
        }
        publish true
    }
    root.files = []
    root.files.add([
            'includePattern': 'build/libs/(.*\\.(jar|pom))',
            'uploadPattern' : "$packageDir/$VERSION_CODE/\$1",
            'matrixParams'  : [
                    'override': 1
            ]
    ])

    def jsonFile = new File("$buildDir/descriptor.json")
    if (!jsonFile.parentFile.exists()) jsonFile.parentFile.mkdirs()
    jsonFile.write(builder.toPrettyString())
}

build.dependsOn('writeDescriptor')