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.
</p>
<p>
If you do not specify this parameter, it defaults to the Amazon Web Services account of the identity used to call
the operation.
</p>
<p>
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, and 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, then don't specify this parameter,
and 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.</p>
       <p>
       If you do not specify this parameter, it defaults to the Amazon Web Services account of the identity used
       to call the operation.
       </p>
       <p>
       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, and 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, then don't specify this
       parameter, and 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/GetAlternateContactRequest.java