public void setAccountId(String accountId) {
        this.accountId = 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>

@param accountId
       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