this.values = new @Nullable Object[initialCapacity];
    }

    private void ensureCapacity(int minCapacity) {
      if (minCapacity > keys.length) {
        int newCapacity = ImmutableCollection.Builder.expandedCapacity(keys.length, minCapacity);
        this.keys = Arrays.copyOf(keys, newCapacity);
        this.values = Arrays.copyOf(values, newCapacity);
      }
    }

    /**

  }

  /**
   * Returns a {@link Collector} that accumulates elements into an {@code ImmutableSortedMap} whose
   * keys and values are the result of applying the provided mapping functions to the input
   * elements.
   *
   * <p>If the mapped keys contain duplicates (according to the comparator), the values are merged
   * using the specified merging function. Entries will appear in the encounter order of the first
   * occurrence of the key.