*     long}, i.e. when {@code x > 2^62}
   * @since 20.0
   */
  public static long ceilingPowerOfTwo(long x) {
    checkPositive("x", x);
    if (x > MAX_SIGNED_POWER_OF_TWO) {
      throw new ArithmeticException("ceilingPowerOfTwo(" + x + ") is not representable as a long");
    }
    return 1L << -Long.numberOfLeadingZeros(x - 1);
  }

  /**

@NullMarked
@GwtCompatible
public class BigIntegerMathTest extends TestCase {
  public void testCeilingPowerOfTwo() {
    for (BigInteger x : POSITIVE_BIGINTEGER_CANDIDATES) {
      BigInteger result = BigIntegerMath.ceilingPowerOfTwo(x);
      assertTrue(BigIntegerMath.isPowerOfTwo(result));
      assertThat(result).isAtLeast(x);
      assertThat(result).isLessThan(x.add(x));
    }
  }

  public void testFloorPowerOfTwo() {

      // ends up being used to compute a "threshold" size, beyond which the internal table
      // will be resized. That threshold is ceilingPowerOfTwo(capacity*loadFactor), where
      // loadFactor is 0.75 by default. So with the calculation here we ensure that the
      // threshold is equal to ceilingPowerOfTwo(expectedSize). There is a separate code
      // path when the first operation on the new map is putAll(otherMap). There, prior to

      // ends up being used to compute a "threshold" size, beyond which the internal table
      // will be resized. That threshold is ceilingPowerOfTwo(capacity*loadFactor), where
      // loadFactor is 0.75 by default. So with the calculation here we ensure that the
      // threshold is equal to ceilingPowerOfTwo(expectedSize). There is a separate code
      // path when the first operation on the new map is putAll(otherMap). There, prior to