The Spigot API does not provide a method to create an explosion with a source entity.
Here is the javadoc related to explosions: https://hub.spigotmc.org/javadocs/bukkit/org/bukkit/World.html#createExplosion-double-double-double-float-
However, the NMS method to create an explosion is:

public Explosion createExplosion(@Nullable Entity entity, DamageSource damagesource, double d0, double d1, double d2, float f, boolean flag, Effect explosion_effect)

 The CraftBukkit implementation always provides a null entity for the first field, and I'm wondering why isn't there methods to create explosions with a source entity.