Validate input parameters

[dimitrystd]

We got bug when user code passed empty value into uploadFile() and getStatus(). SDK generated wrong api call and failed with error.

DoD:

• Each api method must validate input parameters. An example:
  • not empty
  • not null
  • valid URL
• This task for all APIs, not only for File API
• Patch is applied to all recent SDK versions (1.9, 2.0)