Hello @armensanoyan 
There are 4 parameters in this order for the apoc.merge.node() function:
- label: represents the labels you want to set on the node
- identProps: represents the properties that uniquely identify the node
- onCreateProps: represents the properties you want to set when the node is created
- onMatchProps: represents the properties you want to set when the node is matched (so the node is already in the database)
Regards,
Cobra