null if the application does not specify any absolute or relative ordering.
In the source code there is a constant ServletContext.ORDERED_LIBS, but I see no code where it were used.
My understanding is that the list should contain just the jar names, e.g. ["foo.jar", "bar.jar"] and be absent if there is no ordering.
This has been fixed in trunk and 7.0.x and will be included in 7.0.35 onwards.