public int getTotalTagSizeBytes() {
    if (variant == Variant.NO_PREFIX) {
      return getCryptographicTagSizeBytes();
    }
    if (variant == Variant.TINK) {
      return getCryptographicTagSizeBytes() + 5;
    }
    if (variant == Variant.CRUNCHY) {
      return getCryptographicTagSizeBytes() + 5;
    }
    if (variant == Variant.LEGACY) {
      return getCryptographicTagSizeBytes() + 5;
    }
    throw new IllegalStateException("Unknown variant");
  }
Returns the size of the security relevant tag plus the size of the prefix with which this key
prefixes every tag.
java_src/src/main/java/com/google/crypto/tink/mac/HmacParameters.java