[Blocking] minecraft:explode's maxResistance doesn't work

Verification builds: 

1.6.0.6_beta-17 (Release_1031146)

Summary: 

minecraft:explode's maxResistance doesn't seem to work.

The documentation says: "Blocks with less resistance than this value will be broken by the explosion"

That makes me think that if I set the value to say, 3, that any block with blastResistance >= 3 wouldn't be destroyed by the explosion, but that is not the case. 

Impact: Blocked on development in a map that needs the player to use TNT to destroy some blocks, but not others.

Repro Steps:

1. Pull up attached map.
2. /teleport 321 69 116
3. Notice in the behavior pack, that we have TNT's explode set with maxResistance = 3.
4. Light TNT with flint & steel

Observed Results: Both sand (blastResistance 2.5) and sandstone (blastResistance 4) are destroyed. Actually even the bedrock is destroyed, and it usually isn't, so perhaps the documentation is just wrong?

Expected Results: Only the sand should be destroyed.

Screenshots/Videos attached: No

SideNote: We'd be totally happy if instead of this, you could put a filter with blocktypes on it instead, but this being fixed would suffice.