(it work in 1.12.2)

1.edit an advancement`s criteria and requirements to

"criteria":
{ "explosion":
{ "trigger": "minecraft:entity_hurt_player",
"conditions":
{ "damage":
{ "source_entity":{"nbt":"

{ignited:1b}

"},
"type":

{"is_explosion":true}

,
"blocked":true
}
}
}
},
"requirements":
[
["explosion"]
]

2.get creeper spawn egg,flint_and_steel ,shield and changing your gamemode to survive
3.let creeper explode it self and block its damage with shield (it should not trigger)[not trigger in this version]
4.ignite the creeper and block the damage with shield (it should trigger)[still not trigger]

5.edit this advancement`s criteria and requirements to
"criteria":
{ "explosion":
{ "trigger": "minecraft:entity_hurt_player",
"conditions":
{ "damage":
{ "source_entity":{"nbt":"

{\"ignited\":1b}

"},
"type":

{"is_explosion":true}

,
"blocked":true
}
}
}
},
"requirements":
[
["explosion"]
]

6.do step 3,4 again,and both still not work