Try to add sources

OsmAnd-api/build.gradle

@@ -33,4 +33,13 @@ android {
 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
+}
+
+artifacts {
+    archives sourcesJar
 }