IPropertyBag
Gets a collection containing all the keys in the property set
Adds a key/value pair to the property bag
Gets a flag indicating whether the specified key has
any entries in the property set.
Gets a single value for a key, using the first
one if multiple values are present and returning
null if the value is not found.
Sets the value for a key, removing any other
values that are already in the property set.
Tries to retrieve list of values.