add configs for jitpack publishing

android/build.gradle

@@ -75,4 +75,6 @@ dependencies {
     // Add Roboelectric dependencies.
     testImplementation 'org.robolectric:robolectric:4.5'
     testImplementation 'androidx.test:core:1.3.0'
-}
+}
+
+apply from: rootProject.file('gradle/jitpack-android.gradle')

core/build.gradle

@@ -27,4 +27,6 @@ dependencies {
 
     testImplementation platform("org.junit:junit-bom:5.7.2")
     testImplementation "org.junit.jupiter:junit-jupiter"
-}
+}
+
+apply from: rootProject.file('gradle/jitpack-core.gradle')

gradle/jitpack-android.gradle

@@ -0,0 +1,26 @@
+// Needed for Jitpack (ref: https://github.com/jitpack/gradle-modular/blob/6816f11/build.gradle)
+apply plugin: 'maven'
+
+task sourcesJar(type: Jar) {
+    classifier = 'sources'
+    from android.sourceSets.main.java.srcDirs
+}
+
+task javadoc(type: Javadoc) {
+    failOnError false
+    source = android.sourceSets.main.java.sourceFiles
+    classpath += project.files(android.getBootClasspath().join(File.pathSeparator))
+    classpath += configurations.compile
+}
+
+// build a jar with javadoc
+task javadocJar(type: Jar, dependsOn: javadoc) {
+    classifier = 'javadoc'
+    from javadoc.destinationDir
+}
+
+// Attach Javadocs and Sources jar
+artifacts {
+    archives sourcesJar
+    archives javadocJar
+}

gradle/jitpack-core.gradle

@@ -0,0 +1,18 @@
+// Needed for Jitpack (ref: https://github.com/jitpack/gradle-modular/blob/6816f11/build.gradle)
+apply plugin: 'maven'
+
+task sourcesJar(type: Jar, dependsOn: classes) {
+    classifier = 'sources'
+    from sourceSets.main.allSource
+}
+
+task javadocJar(type: Jar, dependsOn: javadoc) {
+    classifier = 'javadoc'
+    from javadoc.destinationDir
+}
+
+// Attach Javadocs and Sources jar
+artifacts {
+    archives sourcesJar
+    archives javadocJar
+}