There are two ways in which a kaa app sdk can be downloaded from the sandbox. One from the front panel of the kaa sandbox and the second from the admin panel.
These two java sdk downloads for zeppelin demo are very different. The first method gives lib and src directories after extraction but the 2nd gives com, org and META-INF directories. The first download compiles perfectly fine with mvn but the second does not compile at all. Why are these two downloads different?
Also, whenever I make changes to any schema, can I download the changed sdk from the sandbox front panel or do I have to always download it from the admin panel?
Using "Source" button on the Sandbox page you download the source code of an application and the Endpoint SDK. If you change some schemes and create new Endpoint SDK, you must generate and download it at Administration UI page and replace existing Endpoint SDK in your project lib directory. Read Your first Kaa application and Using Kaa endpoint SDKs/Java.