Interface for anything that can contain a DBObject. If a class implements
this interface then support such as the explorers (structure pane) and any
context menu support will function.
Returns the contained object. In general this should not be null, but as
DBObjectNode implementations can exist outside of the context of a provider,
then if the provider is null it is not safe to assume that this will return
an object.
Initialises a new node. This is used by the create object dialogs when a
new object is created that shouldn't be immediately saved - e.g. PL/SQL
or XML Schema. The node is initialised and then opened in an editor, the
save of the editor will be the first commit of the object to the backend.