Add JavaDoc tasks

Author: koji-1009

studyplus-android-sdk2/build.gradle

@@ -48,3 +48,28 @@ dependencies {
     testImplementation "org.jetbrains.kotlin:kotlin-test-junit:$kotlin_version"
     testImplementation "com.squareup.okhttp3:mockwebserver:$okhttp"
 }
+
+task sourcesJar(type: Jar) {
+    classifier = 'sources'
+    from android.sourceSets.main.java.sourceFiles
+}
+
+task javadoc(type: Javadoc) {
+    source = android.sourceSets.main.java.sourceFiles
+    classpath += project.files(android.getBootClasspath().join(File.pathSeparator))
+}
+
+task javadocJar(type: Jar, dependsOn: javadoc) {
+    classifier = 'javadoc'
+    from javadoc.destinationDir
+}
+
+task classesJar(type: Jar) {
+    from "$buildDir/intermediates/classes/release"
+}
+
+artifacts {
+    archives classesJar
+    archives javadocJar
+    archives sourcesJar
+}