code: @Override
    public void writeHeader(RandomAccessFile file) throws IOException {
      super.writeHeader(file);
      file.writeInt(this.dirCapacity);
      file.writeInt(this.leafCapacity);
      file.writeInt(this.dirMinimum);
      file.writeInt(this.leafMinimum);
      file.writeInt(this.emptyPagesSize);
      file.writeInt(this.largestPageID);
    }
docs: Writes this header to the specified file. Writes the integer values of
  {@link #dirCapacity}, {@link #leafCapacity}, {@link #dirMinimum},
  {@link #leafMinimum} and {@link #emptyPagesSize} to the file.