Syntax
set anObject = map.setMapValue(aKey, anotherObject)
SemanticsWithin map map replace the object of the map entry identified by akey with anotherObject. The operation returns the old content (being replaced). If the addressed key does not exists, the item is appended to the map.
SubstitutablesanObjectoptional: The map entry being replaced. 
map

An object of type Map.

aKeyKey value identifying the map entry.
anotherObjectThe object to replace the map entry with.
Examples
create oldAddress;
  
create newAddress;
set newAddress.street = "99, Kings Road";
set newAddress.town = "London";
  
set oldAddress = hashMap.setMapValue("John Smith", newAddress);
oldAddress and newAddress are objects of type Address. name is the key of the map.

Example File (Builder project E2E Action Language/Map):

<your example path>\E2E Action Language\map\uml\mapBenchmark.xml