public int getMacLength() {
        return macLength;
    }
Creates an Hkdf instance which will use hmacName as the name for the underlying
HMAC algorithm, which will be located using normal JCA precedence rules.
<p>
@param hmacName the name of the HMAC algorithm to use
@throws NoSuchAlgorithmException if hmacName is not a valid HMAC name
common/src/main/java/org/conscrypt/Hkdf.java