public AssociateMacSecKeyRequest withCkn(String ckn) {
        setCkn(ckn);
        return this;
    }
<p>
The MAC Security (MACsec) CKN to associate with the dedicated connection.
</p>
<p>
You can create the CKN/CAK pair using an industry standard tool.
</p>
<p>
The valid values are 64 hexadecimal characters (0-9, A-E).
</p>
<p>
If you use this request parameter, you must use the <code>cak</code> request parameter and not use the
<code>secretARN</code> request parameter.
</p>

@param ckn
       The MAC Security (MACsec) CKN to associate with the dedicated connection.</p>
       <p>
       You can create the CKN/CAK pair using an industry standard tool.
       </p>
       <p>
       The valid values are 64 hexadecimal characters (0-9, A-E).
       </p>
       <p>
       If you use this request parameter, you must use the <code>cak</code> request parameter and not use the
       <code>secretARN</code> request parameter.
@return Returns a reference to this object so that method calls can be chained together.
aws-java-sdk-directconnect/src/main/java/com/amazonaws/services/directconnect/model/AssociateMacSecKeyRequest.java