private static void checkIsBlockCompressed(File input) throws IOException {
  if (!isBlockCompressed(input)) {
    throw new IllegalArgumentException("File: " + input.getPath() + " is not in block compressed gzip format");
  }
}

private static void checkIsBlockCompressed ( File input ) throws IOException { if ( ! isBlockCompressed ( input ) ) { throw new IllegalArgumentException ( "File: " + input . getPath ( ) + " is not in block compressed gzip format" ) ; } }
confirm given file is block compressed
