The nominations are in for the 16th annual Americana Awards, to be held Sept. 13 in Nashville as the signature event of AmericanaFest — and in at least one category, they tell a tale of how this progressive yet traditionalist community is rising to the political challenges of a complicated historical moment. Four of the five releases in the Album of the Year category have protest at their core, demonstrating how the genre is stretching itself even as it builds on long-established artistic family ties.