public java.util.List<String> getAccounts() {
        if (accounts == null) {
            accounts = new com.amazonaws.internal.SdkInternalList<String>();
        }
        return accounts;
    }
<p>
[Self-managed permissions] The accounts in which to update associated stack instances. If you specify accounts,
you must also specify the Amazon Web Services Regions in which to update stack set instances.
</p>
<p>
To update <i>all</i> the stack instances associated with this stack set, don't specify the <code>Accounts</code>
or <code>Regions</code> properties.
</p>
<p>
If the stack set update includes changes to the template (that is, if the <code>TemplateBody</code> or
<code>TemplateURL</code> properties are specified), or the <code>Parameters</code> property, CloudFormation marks
all stack instances with a status of <code>OUTDATED</code> prior to updating the stack instances in the specified
accounts and Amazon Web Services Regions. If the stack set update does not include changes to the template or
parameters, CloudFormation updates the stack instances in the specified accounts and Amazon Web Services Regions,
while leaving all other stack instances with their existing stack instance status.
</p>

@return [Self-managed permissions] The accounts in which to update associated stack instances. If you specify
        accounts, you must also specify the Amazon Web Services Regions in which to update stack set
        instances.</p>
        <p>
        To update <i>all</i> the stack instances associated with this stack set, don't specify the
        <code>Accounts</code> or <code>Regions</code> properties.
        </p>
        <p>
        If the stack set update includes changes to the template (that is, if the <code>TemplateBody</code> or
        <code>TemplateURL</code> properties are specified), or the <code>Parameters</code> property,
        CloudFormation marks all stack instances with a status of <code>OUTDATED</code> prior to updating the
        stack instances in the specified accounts and Amazon Web Services Regions. If the stack set update does
        not include changes to the template or parameters, CloudFormation updates the stack instances in the
        specified accounts and Amazon Web Services Regions, while leaving all other stack instances with their
        existing stack instance status.
aws-java-sdk-cloudformation/src/main/java/com/amazonaws/services/cloudformation/model/UpdateStackSetRequest.java