Free Throw

[Nevadaref]

BITS explained it, the citation is rule 6-4-3d.
. . . Alternating-possession throw-ins shall be from the out-of-bounds spot nearest to where the ball was located. An alternating-possession throw-in shall result when:
a. A held ball occurs.
b. The ball goes out of bounds, as in 7-3.
c. A simultaneous free-throw violation occurs.
d. A live ball lodges between the backboard and ring or comes to rest on the flange, unless a free throw or throw-in follows.

Notice that the part in red also covers the final FT attempt on technical fouls, intentional personal fouls, and any other situation in which the lane spaces are unoccupied.