This is my default maven push gradle for my java projects

maven_push.gradle

apply plugin: 'maven'
apply plugin: 'signing'

def isReleaseBuild() {
    return VERSION_NAME.contains("SNAPSHOT") == false
}

def getRepositoryUrl() {
    if(isReleaseBuild()) {
        println 'RELEASE BUILD'
        return "https://oss.sonatype.org/service/local/staging/deploy/maven2/"
    } else {
        println 'DEBUG BUILD'
        return "https://oss.sonatype.org/content/repositories/snapshots/"
    }
}

def getRepositoryUsername() {
    return hasProperty('NEXUS_USERNAME') ? NEXUS_USERNAME : ""
}

def getRepositoryPassword() {
    return hasProperty('NEXUS_PASSWORD') ? NEXUS_PASSWORD : ""
}

afterEvaluate { project ->
    uploadArchives {
        repositories {
            mavenDeployer {
                beforeDeployment { MavenDeployment deployment -> signing.signPom(deployment) }

                pom.groupId = GROUP
                pom.artifactId = POM_ARTIFACT_ID
                pom.version = VERSION_NAME

                repository(url: getRepositoryUrl()) {
                    authentication(userName: getRepositoryUsername(), password: getRepositoryPassword())
                }

                pom.project {
                    name POM_NAME
                    packaging POM_PACKAGING
                    description POM_DESCRIPTION
                    url POM_URL

                    scm {
                        url POM_SCM_URL
                        connection POM_SCM_CONNECTION
                        developerConnection POM_SCM_DEV_CONNECTION
                    }

                    licenses {
                        license {
                            name POM_LICENCE_NAME
                            url POM_LICENCE_URL
                            distribution POM_LICENCE_DIST
                        }
                    }

                    developers {
                        developer {
                            id "leorossetto"
                            name "Leonardo Rossetto"
                        }
                    }
                }
            }
        }
    }

    signing {
        required { isReleaseBuild() && gradle.taskGraph.hasTask("uploadArchives") }
        sign configurations.archives
    }

    task javadocs(type: Javadoc) {
        source = 'src/main/java'
    }

    task javadocsJar(type: Jar, dependsOn: javadocs) {
        classifier = 'javadoc'
        from javadocs.destinationDir
    }

    task sourcesJar(type: Jar) {
        classifier = 'sources'
        from 'src/main/java'
    }

    artifacts {
        archives sourcesJar
        archives javadocsJar
    }

}