Javaでresources化のファイルを取得する

ReosurcesGetter.java

public final class ReosurcesGetter {
    public List<File> get(String path, String extension) {
        File rootFile = new File(getClass().getResource(path).getPath());
        return getRecursiveFiles(rootFile, extension);
    }

    // ファイルを再帰的に取得
    private List<File> getRecursiveFiles(File file, String extension) {
        Optional<File[]> maybeFiles = Optional.ofNullable(file.listFiles());
        List<File> result = new ArrayList<>();
        
        maybeFiles.ifPresent(files -> { 
            Arrays.asList(files)
                    .stream()
                    .filter(f -> f.isFile())
                    .filter(f -> hasTargetExtention(f.getName(), extension))
                    .forEach(f -> result.add(f));
    
            Arrays.asList(files)
                    .stream()
                    .filter(f -> f.isDirectory())
                    .forEach(f -> result.addAll(getRecursiveFiles(f, extension)));
        });

        return result;
    }

    private boolean hasTargetExtention(String fineName, String extension) {
        String[] arr = fineName.split("\\.");
        return arr[arr.length - 1].equals(extension);
    }
}