Fixed project gradle settings.

scripts/publish-mavencentral.gradle

@@ -1,5 +1,5 @@
 task androidSourcesJar(type: Jar) {
-    classifier = 'sources'
+    archiveClassifier.set("sources")
     from android.sourceSets.main.java.source
 }
 
@@ -36,6 +36,13 @@ if (secretPropsFile.exists()) {
     ext["ossrhPassword"] = System.getenv('OSSRH_PASSWORD')
 }
 
+nexusStaging {
+    packageGroup = PUBLISH_GROUP_ID
+    stagingProfileId = '2097bad464f778'
+    username = ossrhUsername
+    password = ossrhPassword
+}
+
 publishing {
     publications {
         release(MavenPublication) {