public int getCryptographicTagSizeBytes() {
    return tagSizeBytes;
  }
Returns the size of the tag which is computed cryptographically from the message.

<p>This may differ from the total size of the tag, as for some keys, Tink prefixes the tag with
a key dependent output prefix.
java_src/src/main/java/com/google/crypto/tink/mac/HmacParameters.java