@Override public String extractMetadata(File file) { Validate.notNull(file, "File can not be null"); Validate.notNull(file.getAbsolutePath(), "File path can not be null"); Validate.isTrue(file.isFile(), "File: " + file.getName() + " was not found"); Metadata metadata = slang.extractMetadata(SlangSource.fromFile(file)); return prettyPrint(metadata); }