I was creating a standard elevated mob system that included adding 8-block long water streams that led to a 4x4 hole. When my player was being dragged towards the 4x4 air blocks, I naturally started walking towards a wall next to the water stream so I could jump away from death as soon as I could. But, when the water stream ended I didn't need to jump, since my character auto jumped to a ground of blocks at the same level as the blocks below me. (NOTE: I did notice that this didn't happen if the blocks I would have auto jumped to were covered in water.)

What I expected to happen was...

When I had reached the air blocks, to fall down if I didn't press the space bar.

What actually happened was...

The game automatically made me jump to safety, if I was walking towards a wall. I fall if I don't press anything.

1. Create a water stream that goes for 8 blocks and reaches an air block;
2. Have a 2- high wall by the end of that same water stream;
3. Have a block diagonally from the last block below the water stream, next to the wall, to the side of the air block.
3. Flow down the water stream and start going forward with your player, towards the wall, pressing against it (diagonally forward or straight forward, it doesn't matter);
4. Player will jump towards the block beside the air block automatically, without having to press the space bar.

Since the description is tricky, I attached an image of how I was proceeding just before I got auto jumped.