code: @Beta
    public static MappedByteBuffer map(File file) throws IOException {
      checkNotNull(file);
      return map(file, MapMode.READ_ONLY);
    }
docs: Fully maps a file read-only in to memory as per {@link
  FileChannel#map(java.nio.channels.FileChannel.MapMode, long, long)}.
  
  <p>Files are mapped from offset 0 to its length.
  
  <p>This only works for files ≤ {@link Integer#MAX_VALUE} bytes.
  
  @param file the file to map
  @return a read-only buffer reflecting {@code file}
  @throws FileNotFoundException if the {@code file} does not exist
  @throws IOException if an I/O error occurs
  @see FileChannel#map(MapMode, long, long)
  @since 2.0