public void testKeySet_nullToArray() {
    for (LoadingCache<Object, Object> cache : caches()) {
      Set<Object> keys = cache.asMap().keySet();
      assertThrows(NullPointerException.class, () -> keys.toArray((Object[]) null));
      checkEmpty(cache);
    }
  }

  public void testKeySet_addNotSupported() {
    for (LoadingCache<Object, Object> cache : caches()) {

  }

  @GwtIncompatible // Iterables.toArray(Iterable, Class)
  public void testToArrayEmpty() {
    Iterable<String> iterable = emptyList();
    String[] array = Iterables.toArray(iterable, String.class);
    assertTrue(Arrays.equals(new String[0], array));
  }

  @GwtIncompatible // Iterables.toArray(Iterable, Class)
  public void testToArraySingleton() {

                    return matcher.group(3);
                }
            } else if (v == version) {
                return matcher.group(3);
            }
            return null;
        }).filter(s -> s != null).toArray(n -> new String[n]);
    }

    /**
     * Gets the major version number of the current Java runtime.
     * For Java 8 and below, returns the minor version (e.g., 8 for Java 1.8).

            if (credential instanceof KerberosKey) {
                serverKeys.add((KerberosKey) credential);
            }
        }

        return serverKeys.toArray(new KerberosKey[0]);
    }

    /**
     * Retrieves a specific Kerberos key by key type.
     *
     * @param keyType the encryption type of the key to retrieve

  }

  @Override
  public @Nullable Object[] toArray() {
    if (needsAllocArrays()) {
      return new Object[0];
    }
    Set<E> delegate = delegateOrNull();
    return (delegate != null) ? delegate.toArray() : Arrays.copyOf(requireElements(), size);
  }

  @CanIgnoreReturnValue
  @Override
  @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations

  }

  /** Returns an immutable array containing the given values, in order. */
  public static ImmutableLongArray copyOf(Collection<Long> values) {
    return values.isEmpty() ? EMPTY : new ImmutableLongArray(Longs.toArray(values));
  }

  /**
   * Returns an immutable array containing the given values, in order.
   *
   * <p><b>Performance note:</b> this method delegates to {@link #copyOf(Collection)} if {@code

  }

  /** Returns an immutable array containing the given values, in order. */
  public static ImmutableIntArray copyOf(Collection<Integer> values) {
    return values.isEmpty() ? EMPTY : new ImmutableIntArray(Ints.toArray(values));
  }

  /**
   * Returns an immutable array containing the given values, in order.
   *
   * <p><b>Performance note:</b> this method delegates to {@link #copyOf(Collection)} if {@code

    @Override
    public boolean retainAll(Collection<?> collection) {
      return standardRetainAll(collection);
    }

    @Override
    public Object[] toArray() {
      return standardToArray();
    }

    @Override
    public <T> T[] toArray(T[] array) {
      return standardToArray(array);
    }

    @Override
    public String toString() {
      return standardToString();
    }
  }

        final String[] loggerNames = loggerNamePrefix != null
                ? Arrays.stream(loggerNamePrefix.split(",")).map(String::trim).filter(s -> s.length() > 0).toArray(n -> new String[n])
                : new String[0];
        return new ErrorToWarnRewritePolicy(loggerNames);
    }

  public static <T extends @Nullable Object> T[] toArray(
      Iterable<? extends T> iterable, Class<@NonNull T> type) {
    return toArray(iterable, ObjectArrays.newArray(type, 0));
  }

  static <T extends @Nullable Object> T[] toArray(Iterable<? extends T> iterable, T[] array) {
    Collection<? extends T> collection = castOrCopyToCollection(iterable);
    return collection.toArray(array);
  }

  /**