Since i started developing applications for android i noticed there were some undocumented apis. Google does reccomend to not use these apis but since there are no "other nice ways" to achieve some tasks sometimes they are useful ( but still unreccomended)
It's the case of the Google Calendar Apis. Out there you can find a lot of docs about these undocumented & unsupported apis but you'll get some troubles if google decides to change them.
For example if you want to add an "event" to the calendar programmatically you can follow the snippet below which is SDK proof. In fact i did ( It's not refactored for better reading ) write some code that would work on Sdk from 1.5 to 2.2 ( aka Froyo ) solving the provider issue on froyo and above.
Hope it helps to solve the problem about google calendar in froyo