Adding Google Analytics script to html files

GoogleAnalyticsTagIdAdded.java

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

public class App {

    public static void main(String[] args) throws IOException {
        if (args.length != 2) {
            throw new IllegalArgumentException();
        }

        String googleAnalyticsTagId = args[0];
        String startLocation = args[1];

        String googleAnalytics =
            """

                <!-- Global site tag (gtag.js) - Google Analytics -->
                <script async src="https://www.googletagmanager.com/gtag/js?id=%s">
                </script>
                <script>
                  window.dataLayer = window.dataLayer || [];
                  function gtag(){dataLayer.push(arguments);}
                  gtag('js', new Date());

                  gtag('config', '%s');
                </script>

            """.formatted(googleAnalyticsTagId, googleAnalyticsTagId);

        List<Path> paths = Files.find(
                Paths.get(startLocation),
                Integer.MAX_VALUE,
                (p, basicFileAttributes) -> p.getFileName().toString().endsWith(".html"))
                .collect(Collectors.toList());

        for (Path path : paths) {
            List<String> contents = Files.readAllLines(path, StandardCharsets.UTF_8);

            List<String> newContents = new ArrayList<>();
            for (String content : contents) {
                if (content.contains("</head>")) {
                    newContents.add(googleAnalytics + content);
                } else {
                    newContents.add(content);
                }
            }

            Files.write(path, newContents, StandardCharsets.UTF_8, StandardOpenOption.WRITE);
        }

        System.out.println("done");
    }
    
}