public IntegerFieldValue putUnChecked(K key, IntegerFieldValue weight) {
        return map.put(key, weight);
    }
Add a key with an associated weight to this set. If the key is already present in this set, the previous
association is replaced.

@param key    the key to add
@param weight the weight to associate with this key
@return the weight that was previously associated with this key, or null (if there was no previous key)
document/src/main/java/com/yahoo/document/datatypes/WeightedSet.java