You can place frogspawn over boats on the water:

Steps to Reproduce:

1. In a body of water, spawn a boat
2. Stand over, or generally above the boat
3. While aiming on top of it, use a frogspawn

Observed Behavior:

The frogspawn will place on top of the boat.

Expected Result:

Because the boat is the first targeted right-click interaction, when it fails (due to shift click being held), nothing would happen. The frog spawn would only be valid for placement if the player is directly targeting water.

Screenshots/Videos:

frogspawn_on_boats.mp4

Notes:

1. This does not occur for lily pads.
2. Related to MC-273178 MC-667 (fixed)