Map's are collections. They use generics to specify the types they're dealing with.
To declare a Map you need Map<K,V> where 'K' is the object type for the key, and 'V' is the object type for the value. Keys stored in the Map must be unique. Map entries are "registered" using the put() method, and "retrieved" with the get() method.
Blackboard blackboard = new Blackboard(...);
// asuming your Blackboard class has a Map variable by the name of "map"
blackboard.map.put( "unique name", variable );
blackboard.map.put( "pointLight", pointLight );