Put provides and requires code to basic Flow

Code that calculates provides and requires for flow is almost
identical for all patterns, so this change makes it completely
identical and puts it to the base class. Other patterns are
still allowed to override these properties for sake of customization
or optimization.

Change-Id: I6e875e863047b5287ec727fc9a491f252f144ecf
Merge "Put provides and requires code to basic Flow"