switched to maven-publish

The upgrade was required since `maven` doesn't work with Gradle 7.

Followed the following documentation:
* [Android - Use the Maven Publish plugin](https://developer.android.com/studio/build/maven-publish-plugin)
* [DSL documentation}(https://docs.gradle.org/current/dsl/org.gradle.api.publish.maven.MavenPublication.html)

Author: jkasten2

OneSignalSDK/onesignal/maven-push.gradle

@@ -17,7 +17,7 @@
  *
  */
 
-apply plugin: 'maven'
+apply plugin: 'maven-publish'
 apply plugin: 'signing'
 
 class Global {
@@ -41,10 +41,6 @@ class Global {
     static def RELEASE_REPOSITORY_URL = 'https://oss.sonatype.org/service/local/staging/deploy/maven2'
 }
 
-def isReleaseBuild() {
-    return !Global.VERSION_NAME.contains("SNAPSHOT")
-}
-
 def getRepositoryUsername() {
     return hasProperty('NEXUS_USERNAME') ? NEXUS_USERNAME : ""
 }
@@ -53,47 +49,49 @@ def getRepositoryPassword() {
     return hasProperty('NEXUS_PASSWORD') ? NEXUS_PASSWORD : ""
 }
 
-afterEvaluate { project ->
-    uploadArchives {
+afterEvaluate {
+    publishing {
         repositories {
-            mavenDeployer {
-                beforeDeployment { MavenDeployment deployment -> signing.signPom(deployment) }
-
-                pom.groupId = Global.GROUP_ID
-                pom.artifactId = Global.POM_ARTIFACT_ID
-                pom.version = Global.VERSION_NAME
-
-                repository(url: Global.RELEASE_REPOSITORY_URL) {
-                    authentication(userName: getRepositoryUsername(), password: getRepositoryPassword())
-                }
-                snapshotRepository(url: Global.SNAPSHOT_REPOSITORY_URL) {
-                    authentication(userName: getRepositoryUsername(), password: getRepositoryPassword())
+            maven {
+                url = Global.RELEASE_REPOSITORY_URL
+                credentials {
+                    username = getRepositoryUsername()
+                    password = getRepositoryPassword()
                 }
+            }
+        }
 
-                pom.project {
-                    name Global.POM_NAME
-                    packaging Global.POM_PACKAGING
-                    description Global.POM_DESCRIPTION
-                    url Global.POM_URL
+        publications {
+            release(MavenPublication) {
+                from components.release
+                groupId = Global.GROUP_ID
+                artifactId = Global.POM_ARTIFACT_ID
+                version = Global.VERSION_NAME
+
+                pom {
+                    name = Global.POM_NAME
+                    packaging = Global.POM_PACKAGING
+                    description = Global.POM_DESCRIPTION
+                    url = Global.POM_URL
 
                     scm {
-                        url Global.POM_SCM_URL
-                        connection Global.POM_SCM_CONNECTION
-                        developerConnection Global.POM_SCM_DEV_CONNECTION
+                        url = Global.POM_SCM_URL
+                        connection = Global.POM_SCM_CONNECTION
+                        developerConnection = Global.POM_SCM_DEV_CONNECTION
                     }
 
                     licenses {
                         license {
-                            name Global.POM_LICENCE_NAME
-                            url Global.POM_LICENCE_URL
-                            distribution Global.POM_LICENCE_DIST
+                            name = Global.POM_LICENCE_NAME
+                            url = Global.POM_LICENCE_URL
+                            distribution = Global.POM_LICENCE_DIST
                         }
                     }
 
                     developers {
                         developer {
-                            id Global.POM_DEVELOPER_ID
-                            name Global.POM_DEVELOPER_NAME
+                            id = Global.POM_DEVELOPER_ID
+                            name = Global.POM_DEVELOPER_NAME
                         }
                     }
                 }
@@ -102,25 +100,7 @@ afterEvaluate { project ->
     }
 
     signing {
-        required { isReleaseBuild() && gradle.taskGraph.hasTask("uploadArchives") }
+        required { true }
         sign configurations.archives
     }
-
-    //task androidJavadocs(type: Javadoc) {
-    //source = android.sourceSets.main.allJava
-    //}
-
-    //task androidJavadocsJar(type: Jar, dependsOn: androidJavadocs) {
-    //classifier = 'javadoc'
-    //from androidJavadocs.destinationDir
-    //}
-
-    task androidSourcesJar(type: Jar) {
-        classifier = 'sources'
-        from android.sourceSets.main.java.sourceFiles
-    }
-
-    artifacts {
-        archives androidSourcesJar
-    }
 }