* range [0, k) and ignore the remaining elements.
   */
  private final @Nullable T[] buffer;
  private int bufferSize;

  /**
   * The largest of the lowest k elements we've seen so far relative to this comparator. If
   * bufferSize ≥ k, then we can ignore any elements greater than this value.
   */
  @CheckForNull private T threshold;

    }

    @Override
    public BaseEncoding ignoreCase() {
      BaseEncoding result = ignoreCase;
      if (result == null) {
        Alphabet ignore = alphabet.ignoreCase();
        result = ignoreCase = (ignore == alphabet) ? this : newInstance(ignore, paddingChar);
      }
      return result;
    }

    BaseEncoding newInstance(Alphabet alphabet, @CheckForNull Character paddingChar) {

                    service.awaitTermination(terminationTimeout, timeUnit);
                  } catch (InterruptedException ignored) {
                    // We're shutting down anyway, so just ignore.
                  }
                }
              }));
    }

    @VisibleForTesting
    void addShutdownHook(Thread hook) {
      Runtime.getRuntime().addShutdownHook(hook);
    }
  }

          hashTable[index] = e;
          hashCode += eHash;
          ensureTableCapacity(distinct); // rebuilds table if necessary
          return this;
        } else if (tableEntry.equals(e)) { // not a new element, ignore
          return this;
        }
      }
      // we fell out of the loop due to a long run; fall back to JDK impl
      return new JdkBackedSetBuilderImpl<E>(this).add(e);
    }

    @Override

  }

  // TODO: Re-enable this test after moving to new serialization format in ImmutableMap.
  @J2ktIncompatible
  @GwtIncompatible // SerializableTester
  @SuppressWarnings("unchecked")
  public void ignore_testSerializationNoDuplication_regularImmutableMap() throws Exception {
    // Tests that serializing a map, its keySet, and values only writes the underlying data once.

    Object[] entries = new Object[2000];