push
Puts the effects in the group, giving it the maximum priority.
Acts nearly the same than using add or offer.
Return
the effect pushed
Parameters
effect
the effect
Throws
if the add operation is not supported by this list
if the class of the specified element prevents it from being added to this list
if the specified element is null and this list does not permit null elements
if some property of this element prevents it from being added to this list