Emailer.setBccAddress("") doesn't send Bcc emails

Hello,
setBccAddress doesn't send emails to Bcc. I created this simple groovy script to validate my findings.
When i try to execute the following via Groovy Console.. i can see in the Email Queue that the To and Cc Addresses populated, but Bcc Address is not populated. JM version: 20.5.4.

is this a bug?

import com.avoka.tm.svc.Emailer



new Emailer()

    .setToAddress("john@doe.com")

    .setCcAddress ("mary@doe.com")

    .setBccAddress ("pat@doe.com")

    .setTxnId(1018341L)

    .setSubject("Subject")

    //.setMessage("Hello, John Doe! How are you?")

    //.setMessage("Hello, John and Mary Doe! How are you?")

    .setMessage("Hello, John , Mary and Pat Doe! How are you?")

    .queueEmail()