androidFatJar.gradle

android.libraryVariants.all { variant ->
    tasks.create(name: "fatJar${variant.name.capitalize()}", type: Jar, dependsOn: assembleRelease) {
        doFirst {
            baseName = project.artifactId + "-" + variant.name
            destinationDir = file('output')
            duplicatesStrategy = DuplicatesStrategy.EXCLUDE
            from zipTree(tasks.getByName("package${variant.name.capitalize()}Jar").outputs.files.singleFile)
            def closure = { file ->
                if (file.name.endsWith('.aar')) {
                    println file.name
                    List<File> listJarFiles = zipTree(file).findAll { fileInAar ->
                        fileInAar.name.endsWith('.jar')
                    }
                    def listClassesFilesFromJars = listJarFiles.collect {
                        zipTree(it)
                    }
                    listClassesFilesFromJars
                } else if (file.name.endsWith('.jar')) {
                    return zipTree(file)
                }
            }
            from configurations.compile.files.collect(closure)
            from configurations.getByName("${variant.name}Compile").files.collect(closure)

        }
    }

    tasks.create(name: "collectJars${variant.name.capitalize()}", type: Copy, dependsOn: assembleRelease) {
        delete file("output/outputJars${variant.name.capitalize()}")
        duplicatesStrategy = DuplicatesStrategy.EXCLUDE
        from tasks.getByName("package${variant.name.capitalize()}Jar").outputs.files.singleFile, {
            rename 'classes.jar', project.artifactId + "-" + variant.name + "-" + project.version + ".jar"
        }
        def closure = { file ->
            if (file.name.endsWith('.aar')) {
                println file.name
                zipTree(file).findAll { fileInAar ->
                    fileInAar.name.endsWith('.jar')
                }.each { f ->
                    if(f.name == "classes.jar") {
                        from f, {
                            println f.name
                            rename "classes", file.name.substring(0, file.name.lastIndexOf("."))
                        }
                    } else {
                        from f
                    }

                }
            } else if (file.name.endsWith('.jar')) {
                from file
            }
        }
        configurations.compile.files.collect(closure)
        configurations.getByName("${variant.name}Compile").files.collect(closure)
        into 'output/outputJars' + variant.name.capitalize()
    }
}