How in the world could you ever know that?
We have two codexes published before this, Vaticanus and Sinaiticus that have lists that differ from each other and the modern canon.
We have extant codexes published after this that have the full canon. Again, this is what the Vulgate was - a codification of the modern biblical NT canon.
You can also read the discussion by the Church fathers, and read the discussion surrounding Marcion over the correct canon. While it is true that there was substantial agreement on the content - that bible you have in your hands today owes it’s format to the Vulgate published by the Catholic church in the late 4th and early 5th century.