Atleast on 1.14.4 paper, this seems to often be called with the water as the sourceBlock and the hitFace being the direction the fireball came from a majority of the time.
For example, if the fireball is launched from the east, the hitFace is EAST and we'd need to check that sourceBlock is a fluid and the block west of it is burnable.
Sometimes it works as this code already expects. I'd recommend checking both possibilities to get maximal damage.
Atleast on 1.14.4 paper, this seems to often be called with the water as the sourceBlock and the hitFace being the direction the fireball came from a majority of the time.
For example, if the fireball is launched from the east, the hitFace is EAST and we'd need to check that sourceBlock is a fluid and the block west of it is burnable.
Sometimes it works as this code already expects. I'd recommend checking both possibilities to get maximal damage.