if (copy.isEmpty()) {
          return ImmutableSet.of();
        }
        axesBuilder.add(copy);
      }
      ImmutableList<ImmutableSet<E>> axes = axesBuilder.build();
      ImmutableList<List<E>> listAxes =
          new ImmutableList<List<E>>() {
            @Override
            public int size() {
              return axes.size();
            }

            @Override

        if (copy.isEmpty()) {
          return ImmutableSet.of();
        }
        axesBuilder.add(copy);
      }
      ImmutableList<ImmutableSet<E>> axes = axesBuilder.build();
      ImmutableList<List<E>> listAxes =
          new ImmutableList<List<E>>() {
            @Override
            public int size() {
              return axes.size();
            }

            @Override

 *
 * <p>If the precondition is not met, the {@code Preconditions} method throws an unchecked exception
 * of a specified type, which helps the method in which the exception was thrown communicate that
 * its caller has made a mistake. This allows constructs such as
 *
 * {@snippet :
 * public static double sqrt(double value) {
 *   if (value < 0) {
 *     throw new IllegalArgumentException("input is negative: " + value);
 *   }

 *
 * <p>If the precondition is not met, the {@code Preconditions} method throws an unchecked exception
 * of a specified type, which helps the method in which the exception was thrown communicate that
 * its caller has made a mistake. This allows constructs such as
 *
 * {@snippet :
 * public static double sqrt(double value) {
 *   if (value < 0) {
 *     throw new IllegalArgumentException("input is negative: " + value);
 *   }

    programmatically (with `new Response.Builder()`) you must now always supply
    a message. An empty string `""` is permitted. This value was never null on
    responses returned by OkHttp itself, and it was an old mistake to permit
    application code to omit a message.

 *  The challenge's scheme and realm are now non-null. If you are calling
    `new Challenge(scheme, realm)` you must provide non-null values. These were