*/
          return (ImmutableSet<E>) of(requireNonNull(contents[0]));
        default:
          ImmutableSet<E> result;
          if (hashTable != null && chooseTableSize(size) == hashTable.length) {
            @Nullable
            Object[] uniqueElements =
                shouldTrim(size, contents.length) ? Arrays.copyOf(contents, size) : contents;
            result =
                new RegularImmutableSet<E>(

    final ArrayList<E> contents;

    public Builder() {
      this.contents = Lists.newArrayList();
    }

    Builder(int initialCapacity) {
      this.contents = Lists.newArrayListWithCapacity(initialCapacity);
    }

    @CanIgnoreReturnValue
    @Override
    public Builder<E> add(E element) {
      contents.add(checkNotNull(element));
      return this;
    }

import java.util.function.Consumer;
import java.util.stream.Collector;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A {@link Set} whose contents will never change, with many other important properties detailed at
 * {@link ImmutableCollection}.
 *
 * @since 2.0
 */
@GwtCompatible(serializable = true, emulated = true)