Currently:

• core_renderer::notification accepts either a string of classes to use verbatim, or an array of strings to join with spaces to use on resulting notification HTML.
  • It should be noted that this last use case is NOT DOCUMENTED.
• theme_bootstrapbase_core_renderer::notification accepts a class string, and does not handle an array being passed.
  • The passed class string never actually makes it into the resulting HTML, it is instead mapped to a "suitable" bootstrap class. If no mapping exists, the passed class string is discarded.
  • Not handling an array of classes hides functionality.