This works with the AT loader in SS, but does not work in FML at runtime.
protected net.minecraft.entity.monster.EntityCreeper.field_70833_d #timeSinceIgnited
This is what FML loads, and this is how its supposed to be.
protected net.minecraft.entity.monster.EntityCreeper field_70833_d #timeSinceIgnited
The only difference is that the period between the className and the field/method name has been changed to a space.