public String getAccountId() {
        return this.accountId;
    }
<p>
Specifies the 12-digit account ID number of the Amazon Web Services account that you want to access or modify
with this operation. If you don't specify this parameter, it defaults to the Amazon Web Services account of the
identity used to call the operation. To use this parameter, the caller must be an identity in the <a
href="https://docs.aws.amazon.com/organizations/latest/userguide/orgs_getting-started_concepts.html#account"
>organization's management account</a> or a delegated administrator account. The specified account ID must be a
member account in the same organization. The organization must have <a
href="https://docs.aws.amazon.com/organizations/latest/userguide/orgs_manage_org_support-all-features.html">all
features enabled</a>, and the organization must have <a
href="https://docs.aws.amazon.com/organizations/latest/userguide/using-orgs-trusted-access.html">trusted
access</a> enabled for the Account Management service, and optionally a <a
href="https://docs.aws.amazon.com/organizations/latest/userguide/using-orgs-delegated-admin.html">delegated
admin</a> account assigned.
</p>
<note>
<p>
The management account can't specify its own <code>AccountId</code>. It must call the operation in standalone
context by not including the <code>AccountId</code> parameter.
</p>
</note>
<p>
To call this operation on an account that is not a member of an organization, don't specify this parameter.
Instead, call the operation using an identity belonging to the account whose contacts you wish to retrieve or
modify.
</p>

@return Specifies the 12-digit account ID number of the Amazon Web Services account that you want to access or
        modify with this operation. If you don't specify this parameter, it defaults to the Amazon Web Services
        account of the identity used to call the operation. To use this parameter, the caller must be an identity
        in the <a href=
        "https://docs.aws.amazon.com/organizations/latest/userguide/orgs_getting-started_concepts.html#account"
        >organization's management account</a> or a delegated administrator account. The specified account ID
        must be a member account in the same organization. The organization must have <a href=
        "https://docs.aws.amazon.com/organizations/latest/userguide/orgs_manage_org_support-all-features.html"
        >all features enabled</a>, and the organization must have <a
        href="https://docs.aws.amazon.com/organizations/latest/userguide/using-orgs-trusted-access.html">trusted
        access</a> enabled for the Account Management service, and optionally a <a
        href="https://docs.aws.amazon.com/organizations/latest/userguide/using-orgs-delegated-admin.html"
        >delegated admin</a> account assigned.</p> <note>
        <p>
        The management account can't specify its own <code>AccountId</code>. It must call the operation in
        standalone context by not including the <code>AccountId</code> parameter.
        </p>
        </note>
        <p>
        To call this operation on an account that is not a member of an organization, don't specify this
        parameter. Instead, call the operation using an identity belonging to the account whose contacts you wish
        to retrieve or modify.
aws-java-sdk-account/src/main/java/com/amazonaws/services/account/model/GetRegionOptStatusRequest.java