private static <K extends @Nullable Object, V extends @Nullable Object> Entry<K, V> entry(
      K key, V value) {
    return new AbstractMapEntry<K, V>() {
      @Override
      public K getKey() {
        return key;
      }

      @Override
      public V getValue() {
        return value;
      }
    };
  }

     *
     * @param index
     *            the index
     * @return the key at the specified index
     */
    public K getKeyAt(final int index) {
        return getEntryAt(index).getKey();
    }

    /**
     * Returns the {@link java.util.Map.Entry} at the specified index.
     *
     * @param index
     *            the index

                ? null
                : location.getLocations().entrySet().stream()
                        .collect(Collectors.toMap(
                                e -> e.getKey(),
                                e -> e.getValue() == location ? this : new InputLocation(e.getValue())));
        this.importedFrom = location.getImportedFrom() != null ? new InputLocation(location.getImportedFrom()) : null;
    }

        return packages;
    }

    /**
     * The key that can be used to identify the configuration using the
     * {@link javax.inject.Named} annotation.
     */
    public String getKey() {
        return key;
    }

    /**
     * Returns the configuration for this extension.
     */
    public XmlNode getConfiguration() {
        return configuration;
    }

        "Should not contain null after unsupported putIfAbsent(present, null)");
  }

  @CanIgnoreReturnValue
  private V putIfAbsent(Entry<K, V> entry) {
    return getMap().putIfAbsent(entry.getKey(), entry.getValue());
  }

    void setReleaseUpdatePolicy(ArtifactRepositoryPolicy policy);

    ArtifactRepositoryLayout getLayout();

    void setLayout(ArtifactRepositoryLayout layout);

    String getKey();

    @Deprecated
    boolean isUniqueVersion();

    @Deprecated
    boolean isBlacklisted();

    @Deprecated
    void setBlacklisted(boolean blackListed);

    /**

        // populate the provides section
        Properties provides = model.getProvides();
        for (Entry<Object, Object> provide : provides.entrySet()) {
            String key = (String) provide.getKey();
            String value = (String) provide.getValue();

            if (value == null) {
                throw new MisconfiguredToolchainException(

        classes.put(fullyQualifiedClassName, metaData);
    }

    @Override
    public void each(Closure cl) {
        for (Map.Entry<String, T> entry : classes.entrySet()) {
            cl.call(new Object[]{entry.getKey(), entry.getValue()});
        }
    }

    public void each(Action<? super T> action) {
        for (T t : classes.values()) {
            action.execute(t);
        }
    }

    @SuppressWarnings("unchecked") // we'll only be using getKey and getValue, which are covariant
    Entry<K, V>[] entryArray = (Entry<K, V>[]) Iterables.toArray(entries, EMPTY_ENTRY_ARRAY);
    switch (entryArray.length) {
      case 0:
        return of();
      case 1:
        Entry<K, V> entry = entryArray[0];
        return of(entry.getKey(), entry.getValue());
      default:
        /*

  public void testPut_nullValueSupported() {
    Entry<K, V> nullValueEntry = entry(k3(), null);
    assertNull(
        "putIfAbsent(key, null) should return null",
        getMap().putIfAbsent(nullValueEntry.getKey(), nullValueEntry.getValue()));
    expectAdded(nullValueEntry);
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = ZERO)