Example gradle build that uploads to Bintray and Maven Central

build.gradle

// Useful tasks:
// (default) jar: creates library jar
// fatJar: creates executable jar
// bintrayUpload: performs full publishingTasks/publication

apply plugin: 'java'

wrapper {
    gradleVersion = '4.8.1'
}

repositories {
    mavenCentral()
}

// needed for custom dependencies in the fatJar task
configurations {
    fatJarConf
}

dependencies {
    // EXAMPLE: compile group: 'commons-io', name: 'commons-io', version: '2.6'
    // EXAMPLE: fatJarConf group: 'ch.qos.logback', name: 'logback-classic', version: '1.2.3'
}

//////////////////////////////////////////////////////////
// Configure all of our artifact-generating tasks below //
//////////////////////////////////////////////////////////

// print all of the compiler warnings
tasks.withType(JavaCompile) {
    options.encoding = "UTF-8"
    options.compilerArgs << "-Xlint:all"
}

jar {
    // library clients should configure slf4j themselves
    exclude('logback.xml')
}

task fatJar(type: Jar) {
    description "Build an executable jar with all dependencies included"
    manifest {
        attributes 'Main-Class': project.group + '.MyMainClass'
    }
    from { configurations.compile.collect { it.isDirectory() ? it : zipTree(it) } }
    from { configurations.fatJarConf.collect { it.isDirectory() ? it : zipTree(it) } }

    // output to STDOUT in the executable jar
    from(sourceSets.main.resources) {
        include('logback.xml')
    }
    // this determines the name of the output artifact and how it is imported as a dependency in other builds
    classifier 'executable'
    with jar
}

// these two are required for acceptance in Maven Central
task sourcesJar(type: Jar) {
    description "Build a jar containing just the java source files"
    from sourceSets.main.allJava
    classifier 'sources'
}

task javadocsJar(type: Jar) {
    description "Build a jar containing just the JavaDocs"
    from javadoc
    classifier 'javadoc'
}

// add all of the publishing tasks, which rely on the existence of the artifact tasks above
project.ext.artifactsToPublish = [sourcesJar, javadocsJar, fatJar]
apply from: 'scripts/publishingTasks.gradle'

gradle.properties

group=io.github.yourName
version=0.0.1
description=A description of your project
vcsUrl=https://github.com/yourGithubName/yourProject
website=http://yourproject.io
githubRepo=yourGithubName/yourProject
licenses=Apache 2.0,GPL-3.0
labels=your,project,tags,here
sourceCompatibility=1.8
targetCompatibility=1.8

privateGradle.properties

# place in ~/.gradle/gradle.properties
# ... other properties up here...
org.gradle.daemon=true
org.gradle.parallel=true

# ... the important parts:
# Bintray
bintray.user=yourBintrayName
bintray.key=yourBintrayKey

# Maven central
sonatype.user=yourSonatypeName
sonatype.password=yourSonatypePassword

# GPG
signing.keyId=yourKeyId
signing.password=yourKeyPassword
signing.secretKeyRingFile=/Users/yourName/.gnupg/secring.gpg

publishingTasks.gradle

// place in scripts/publishingTasks.gradle
// Contains publication-related tasks

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.jfrog.bintray.gradle:gradle-bintray-plugin:1.8.3'
    }
}

apply plugin: com.jfrog.bintray.gradle.BintrayPlugin
apply plugin: 'maven'
apply plugin: 'maven-publish'

// TODO: configure this using project properties
def pomConfig = {
    licenses {
        license {
            name "GPL 2.0"
            url "https://www.gnu.org/licenses/gpl-2.0.en.html"
        }
    }
    developers {
        developer {
            id "yourGithubId"
            name "Your Name"
            email "your.name@gmail.com"
        }
    }
    scm {
        url project.vcsUrl
    }
}

publishing {
    publications {
        ProjectPublication(MavenPublication) {
            from components.java
            project.artifactsToPublish.forEach({
                artifact it
            })
            groupId project.group
            artifactId project.name
            version project.version
            pom.withXml {
                def root = asNode()
                root.appendNode('description', project.description)
                root.appendNode('name', project.name)
                root.appendNode('url', project.website)
                root.children().last() + pomConfig
            }
        }
    }
}

bintray {
    user = project.property('bintray.user')
    key = project.property('bintray.key')
    publications =['ProjectPublication']
    pkg {
        repo = 'general'
        name = project.name
        desc = project.description
        userOrg = user
        licenses = project.licenses.split(',')
        vcsUrl = project.vcsUrl
        issueTrackerUrl = project.vcsUrl + "/issues"
        websiteUrl = project.website
        githubRepo = project.githubRepo
        githubReleaseNotesFile = 'CHANGELOG.md'
        labels = project.labels.split(',')
        publicDownloadNumbers = true
        version {
            name = project.version + '-Final'
            desc = project.name + ' ' + project.version + ' final'
            vcsTag = project.version
            gpg {
                sign = true
                passphrase = project.property("signing.password")
            }
            mavenCentralSync {
                user = project.property('sonatype.user')
                password = project.property('sonatype.password')
            }
        }
    }
}

settings.gradle

rootProject.name = 'YourProjectHer'
enableFeaturePreview('STABLE_PUBLISHING')