public void flush() {
    try {
      appendNewlineIfNecessary(leftBuf, leftColumn);
      appendNewlineIfNecessary(rightBuf, rightColumn);
      outputFullLines();
      flushLeft();
      flushRight();
    } catch (IOException ex) {
      throw new RuntimeException(ex);
    }
  }
Flushes the output. If there are more lines of pending output in one column, then the other
column will get filled with blank lines.
android/android_framework/dex-maker/src/main/java/com/android/dx/util/TwoColumnOutput.java