public Certificate withCertificateMode(CertificateMode certificateMode) {
        this.certificateMode = certificateMode.toString();
        return this;
    }
<p>
The mode of the certificate.
</p>
<p>
<code>DEFAULT</code>: A certificate in <code>DEFAULT</code> mode is either generated by Amazon Web Services IoT
Core or registered with an issuer certificate authority (CA) in <code>DEFAULT</code> mode. Devices with
certificates in <code>DEFAULT</code> mode aren't required to send the Server Name Indication (SNI) extension when
connecting to Amazon Web Services IoT Core. However, to use features such as custom domains and VPC endpoints, we
recommend that you use the SNI extension when connecting to Amazon Web Services IoT Core.
</p>
<p>
<code>SNI_ONLY</code>: A certificate in <code>SNI_ONLY</code> mode is registered without an issuer CA. Devices
with certificates in <code>SNI_ONLY</code> mode must send the SNI extension when connecting to Amazon Web
Services IoT Core.
</p>

@param certificateMode
       The mode of the certificate.</p>
       <p>
       <code>DEFAULT</code>: A certificate in <code>DEFAULT</code> mode is either generated by Amazon Web
       Services IoT Core or registered with an issuer certificate authority (CA) in <code>DEFAULT</code> mode.
       Devices with certificates in <code>DEFAULT</code> mode aren't required to send the Server Name Indication
       (SNI) extension when connecting to Amazon Web Services IoT Core. However, to use features such as custom
       domains and VPC endpoints, we recommend that you use the SNI extension when connecting to Amazon Web
       Services IoT Core.
       </p>
       <p>
       <code>SNI_ONLY</code>: A certificate in <code>SNI_ONLY</code> mode is registered without an issuer CA.
       Devices with certificates in <code>SNI_ONLY</code> mode must send the SNI extension when connecting to
       Amazon Web Services IoT Core.
@return Returns a reference to this object so that method calls can be chained together.
@see CertificateMode
aws-java-sdk-iot/src/main/java/com/amazonaws/services/iot/model/Certificate.java