public static Byte[][] filesToBytes(List<String> fileNames) throws IOException {
    List<byte[]> filesDataList = new ArrayList<>();

    for (String fileName : fileNames) {
      File file = new File(fileName);

      if (!file.exists()) {
        throw new FileNotFoundException("Could not find " + file.getCanonicalPath());
      }

      if (file.isDirectory()) {
        File[] childrenFiles = file.listFiles(JAR_FILE_FILTER);
        for (File childrenFile : childrenFiles) {
          // 1. add name of the file as bytes at even index
          filesDataList.add(childrenFile.getName().getBytes());
          // 2. add file contents as bytes at odd index
          filesDataList.add(toByteArray(new FileInputStream(childrenFile)));
        }
      } else {
        filesDataList.add(file.getName().getBytes());
        filesDataList.add(toByteArray(new FileInputStream(file)));
      }
    }

    return filesDataList.stream().map(ArrayUtils::toObject).toArray(Byte[][]::new);
  }
Even thought this is only used in a test, caller of MemberMXBean.processCommand(String, Map,
Byte[][]) will need to use this method to convert a fileList to Byte[][] to call that
deprecated API.

Once that deprecated API is removed, we can delete this method and the tests.
geode-core/src/main/java/org/apache/geode/management/internal/util/ManagementUtils.java