checkState((type == Type.SORTED) == (comparator != null));
  }

  /** Returns an instance which specifies that no ordering is guaranteed. */
  public static <S> ElementOrder<S> unordered() {
    return new ElementOrder<>(Type.UNORDERED, null);
  }

  /**
   * Returns an instance which specifies that ordering is guaranteed to be always be the same across

    checkState((type == Type.SORTED) == (comparator != null));
  }

  /** Returns an instance which specifies that no ordering is guaranteed. */
  public static <S> ElementOrder<S> unordered() {
    return new ElementOrder<>(Type.UNORDERED, null);
  }

  /**
   * Returns an instance which specifies that ordering is guaranteed to be always be the same across

  public <N1 extends N, E1 extends E> ImmutableNetwork.Builder<N1, E1> immutable() {
    NetworkBuilder<N1, E1> castBuilder = cast();
    return new ImmutableNetwork.Builder<>(castBuilder);
  }

  /**
   * Specifies whether the network will allow parallel edges. Attempting to add a parallel edge to a
   * network that does not allow them will throw an {@link UnsupportedOperationException}.
   *
   * <p>The default value is {@code false}.

  public <N1 extends N, V1 extends V> ImmutableValueGraph.Builder<N1, V1> immutable() {
    ValueGraphBuilder<N1, V1> castBuilder = cast();
    return new ImmutableValueGraph.Builder<>(castBuilder);
  }

  /**
   * Specifies whether the graph will allow self-loops (edges that connect a node to itself).
   * Attempting to add a self-loop to a graph that does not allow them will throw an {@link
   * UnsupportedOperationException}.
   *

     */
    Source source() default Source.USER_PROPERTIES;

    /**
     * Specifies the type of the configuration property.
     *
     * @return the fully qualified class name of the property type, defaults to "java.lang.String"
     */
    String type() default "java.lang.String";

    /**
     * Specifies the default value of the configuration property.
     *

	// Together with upload-id-marker, this parameter specifies the multipart upload
	// after which listing should begin.
	KeyMarker string

	// Together with key-marker, specifies the multipart upload after which listing
	// should begin. If key-marker is not specified, the upload-id-marker parameter
	// is ignored.
	UploadIDMarker string

	// When a list is truncated, this element specifies the value that should be

     * Number of results parameter for error page fallback.
     * Specifies how many results to display if redirection fails.
     */
    public String num;

    /**
     * Sort parameter for error page fallback.
     * Defines the sorting order if redirection fails.
     */
    public String sort;

    /**
     * Language parameter for error page fallback.
     * Specifies the language preference if redirection fails.
     */

          <type>String</type>
          <description><![CDATA[
            Specifies that this profile will be activated when a matching JDK is detected.
          ]]></description>
        </field>
        <field>
          <name>os</name>
          <version>1.0.0</version>
          <description><![CDATA[
            Specifies that this profile will be activated when matching OS attributes are detected.

```

`--sftp=cipher-algos=...` specifies the allowed cipher algorithms. 
If unspecified then a sensible default is used.

Valid values: 
```
aes128-ctr
aes192-ctr
aes256-ctr
******@****.***
******@****.***
******@****.***
arcfour256
arcfour128
arcfour
aes128-cbc
3des-cbc
```

  <pluginGroups>
    <!-- pluginGroup
     | Specifies a further group identifier to use for plugin lookup.
    <pluginGroup>com.your.plugins</pluginGroup>
    -->
  </pluginGroups>

  <!-- TODO Since when can proxies be selected as depicted? -->
  <!-- proxies
   | This is a list of proxies which can be used on this machine to connect to the network.
   | Unless otherwise specified (by system property or command-line switch), the first proxy