public String getExternalId() {
        return this.externalId;
    }
<p>
A unique identifier that is required to identify specific groups within your directory. The users of the group
that you associate have access to your Amazon S3 or Amazon EFS resources over the enabled protocols using
Transfer Family. If you know the group name, you can view the SID values by running the following command using
Windows PowerShell.
</p>
<p>
<code>Get-ADGroup -Filter {samAccountName -like "<i>YourGroupName</i>*"} -Properties * | Select SamAccountName,ObjectSid</code>
</p>
<p>
In that command, replace <i>YourGroupName</i> with the name of your Active Directory group.
</p>
<p>
The regular expression used to validate this parameter is a string of characters consisting of uppercase and
lowercase alphanumeric characters with no spaces. You can also include underscores or any of the following
characters: =,.@:/-
</p>

@return A unique identifier that is required to identify specific groups within your directory. The users of the
        group that you associate have access to your Amazon S3 or Amazon EFS resources over the enabled protocols
        using Transfer Family. If you know the group name, you can view the SID values by running the following
        command using Windows PowerShell.</p>
        <p>
        <code>Get-ADGroup -Filter {samAccountName -like "<i>YourGroupName</i>*"} -Properties * | Select SamAccountName,ObjectSid</code>
        </p>
        <p>
        In that command, replace <i>YourGroupName</i> with the name of your Active Directory group.
        </p>
        <p>
        The regular expression used to validate this parameter is a string of characters consisting of uppercase
        and lowercase alphanumeric characters with no spaces. You can also include underscores or any of the
        following characters: =,.@:/-
aws-java-sdk-transfer/src/main/java/com/amazonaws/services/transfer/model/UpdateAccessRequest.java