Try to add library sources

OsmAnd-api/build.gradle

@@ -2,6 +2,7 @@ apply plugin: 'com.android.library'
 apply plugin: 'com.github.dcendents.android-maven'
 
 group = 'net.OsmAnd.OsmAnd-api'
+version = '2.0'
 
 android {
     compileSdkVersion 27
@@ -27,3 +28,17 @@ dependencies {
     implementation fileTree(dir: 'libs', include: ['*.jar'])
     implementation 'com.android.support:support-annotations:27.1.1'
 }
+
+task sourcesJar(type: Jar) {
+    classifier = 'sources'
+    from android.sourceSets.main.java.sourceFiles
+}
+
+task classesJar(type: Jar) {
+    from "$buildDir/intermediates/classes/release"
+}
+
+artifacts {
+    archives classesJar
+    archives sourcesJar
+}