yes, in fact there are several ways to do it depending on your preferences.
APPROACH 1:
You can add a container to the spawner and then spawn it with lock and trap properties, along with contents all in one line using something like this.
metalchest/locked/true/locklevel/60/traptype/explosiontrap/trappower/50/ADD<ginseng/amount/10>/ADD/ARMOR,1,5/ADD/POTION/ADD,0.2/WEAPON,3,5/ADD/<gold/amount/RND,200,500>
that would spawn a locked chest, trap it with an explosion trap of power 50, add a stack of 10 ginseng, a random piece of armor with a level between 1 and 5, a potion, 20% of the time a weapon of level 3-5 , and a random amount of gold between 200-500.
APPROACH 2:
another approach is to have a fixed container that is already placed, and assign the SetItem property to that container. Then you can do the same things as above with the line
SET/locked/true/locklevel/60/traptype/explosiontrap/trappower/50/ADD<ginseng/amount/10>/ADD/ARMOR,1,5/ADD/POTION/ADD,0.2/WEAPON,3,5/ADD/<gold/amount/RND,200,500>
APPROACH 3:
you could also place the spawner inside of the container, assign SetItem to the container and then SET the lock and trap attributes of the container as well as fill it with stuff by just spawning as usual with multiple spawn specifications like this:
SET/locked/true/locklevel/60/traptype/explosiontrap/trappower/50
ginseng/amount/10
ARMOR,1,5
POTION
WEAPON,3,5
gold/amount/RND,200,500
If you do it that way I would probably group spawn them (set the group property or assign them to the same subgroup). If you use the group=true approach, then it wont respawn until all of the spawn is gone.
You could either wait for players to do it, or you could set the duration timer to something so that it would force respawning/resetting of the chest at defined intervals.
Note, that while the approaches are similar, they are not identical. APPROACH 1: since it will execute the SET every OnTick, it will add items each time without removing the previous items. APPROACH 2: will fully respawn the chest and all the items, APPROACH 3: will leave the chest but fully respawn the items (not just continue adding them).
(edit)
sorry, I meant APPROACH 2 will execute the SET on every OnTick and APPROACH 1 will fully respawn the chest with items.