RegularImmutableMap<K, V> empty = (RegularImmutableMap<K, V>) EMPTY;
      return empty;
    } else if (n == 1) {
      // requireNonNull is safe because the first `2*n` elements have been filled in.
      checkEntryNotNull(
          requireNonNull(alternatingKeysAndValues[0]), requireNonNull(alternatingKeysAndValues[1]));
      return new RegularImmutableMap<K, V>(null, alternatingKeysAndValues, 1);
    }

      switch (balanceFactor()) {
        case -2:
          // requireNonNull is safe because right must exist in order to get a negative factor.
          requireNonNull(right);
          if (right.balanceFactor() > 0) {
            right = right.rotateRight();
          }
          return rotateLeft();
        case 2:
          // requireNonNull is safe because left must exist in order to get a positive factor.

              0,
              size,
              (e1, e2) -> {
                // requireNonNull is safe because the first `size` elements have been filled in.
                requireNonNull(e1);
                requireNonNull(e2);
                return comparator.compare(e1.getKey(), e2.getKey());
              });
          // requireNonNull is safe because the first `size` elements have been filled in.

      int j = findNextJ();
      if (j == -1) {
        nextPermutation = null;
        return;
      }
      /*
       * requireNonNull is safe because we don't clear nextPermutation until we're done calling this
       * method.
       */
      requireNonNull(nextPermutation);

      int l = findNextL(j);
      Collections.swap(nextPermutation, j, l);
      int n = nextPermutation.size();

      /*
       * The following requireNonNull calls are safe because we use jlaStackTrace() only if
       * lazyStackTraceIsLazy() returns true.
       */
      @Override
      public StackTraceElement get(int n) {
        return (StackTraceElement)
            invokeAccessibleNonThrowingMethod(
                requireNonNull(getStackTraceElementMethod), requireNonNull(jla), t, n);
      }

      @Override

      /*
       * The following requireNonNull calls are safe because we use jlaStackTrace() only if
       * lazyStackTraceIsLazy() returns true.
       */
      @Override
      public StackTraceElement get(int n) {
        return (StackTraceElement)
            invokeAccessibleNonThrowingMethod(
                requireNonNull(getStackTraceElementMethod), requireNonNull(jla), t, n);
      }

      @Override

      super.addAll(elements);
      return this;
    }

    @CanIgnoreReturnValue
    Builder<E> combine(Builder<E> other) {
      requireNonNull(impl);
      requireNonNull(other.impl);
      /*
       * For discussion of requireNonNull, see the comment on the field.
       *
       * (And I don't believe there's any situation in which we call x.combine(y) when x is a plain

      int j = findNextJ();
      if (j == -1) {
        nextPermutation = null;
        return;
      }
      /*
       * requireNonNull is safe because we don't clear nextPermutation until we're done calling this
       * method.
       */
      requireNonNull(nextPermutation);

      int l = findNextL(j);
      Collections.swap(nextPermutation, j, l);
      int n = nextPermutation.size();

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import static java.util.Objects.requireNonNull;

import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.common.annotations.VisibleForTesting;

      }
      // re-read value, if we get here then we must have observed a TOMBSTONE while trying to add a
      // waiter.
      // requireNonNull is safe because value is always set before TOMBSTONE.
      return getDoneValue(requireNonNull(value));
    }
    // If we get here then we have remainingNanos < SPIN_THRESHOLD_NANOS and there is no node on the
    // waiters list
    while (remainingNanos > 0) {