code: @GwtIncompatible // com.google_voltpatches.common.math.DoubleUtils
    public static boolean isPowerOfTwo(double x) {
      return x > 0.0 && isFinite(x) && LongMath.isPowerOfTwo(getSignificand(x));
    }
docs: Returns {@code true} if {@code x} is exactly equal to {@code 2^k} for some finite integer
  {@code k}.