public void setDomainName(String domainName) {
        this.domainName = domainName;
    }
<p>
Fully qualified domain name (FQDN), such as www.example.com, that you want to secure with an ACM certificate. Use
an asterisk (*) to create a wildcard certificate that protects several sites in the same domain. For example,
*.example.com protects www.example.com, site.example.com, and images.example.com.
</p>
<p>
In compliance with <a href="https://datatracker.ietf.org/doc/html/rfc5280">RFC 5280</a>, the length of the domain
name (technically, the Common Name) that you provide cannot exceed 64 octets (characters), including periods. To
add a longer domain name, specify it in the Subject Alternative Name field, which supports names up to 253 octets
in length.
</p>

@param domainName
       Fully qualified domain name (FQDN), such as www.example.com, that you want to secure with an ACM
       certificate. Use an asterisk (*) to create a wildcard certificate that protects several sites in the same
       domain. For example, *.example.com protects www.example.com, site.example.com, and images.example.com.
       </p>
       <p>
       In compliance with <a href="https://datatracker.ietf.org/doc/html/rfc5280">RFC 5280</a>, the length of the
       domain name (technically, the Common Name) that you provide cannot exceed 64 octets (characters),
       including periods. To add a longer domain name, specify it in the Subject Alternative Name field, which
       supports names up to 253 octets in length.
aws-java-sdk-acm/src/main/java/com/amazonaws/services/certificatemanager/model/RequestCertificateRequest.java