public static FilesApplicationPackage fromFile(File appDir, boolean includeSourceFiles) {
        return new Builder(appDir).preprocessedDir(applicationFile(appDir, preprocessed))
                                  .includeSourceFiles(includeSourceFiles)
                                  .build();
    }
Returns an application package object based on the given application dir

@param appDir application package directory
@param includeSourceFiles read files from source directories /src/main and src/test in addition
                          to the application package location. This is useful during development
                          to be able to run tests without a complete build first.
@return an Application package instance
config-application-package/src/main/java/com/yahoo/config/model/application/provider/FilesApplicationPackage.java