Julian Gough, the poet behind Minecraft's final sequence the End Poem, never legally transfered the rights for the poem to Mojang or subsequently to Microsoft.

Julian Gough recently released a 10,000~ word blog post detailing the events that led up to this outcome, and relinquished all of his personal rights over the poem under a CC0 license, allowing anyone to use the poem as they wish in their own creative or commercial works.

You can read the article here. I recommend it!
If you can't read the article, here's the especially relevant section adressing Microsoft's legal team.

"Significantly altered or removed" — A significant alteration of the poem would include any change that causes it to be more difficult to read or find in the game in a way that is clearly local to the poem (not, for example, simply due to it becoming harder to defeat the Ender Dragon), or any deliberate wording change which changes the meaning of the poem. Making the poem easier to access (for whatever reason) would not qualify as a significant alteration under this definition.