ProcessManager constructor Null safety

1. Flutter
2. process
3. ProcessManager
4. ProcessManager constructor

ProcessManager class

1. Constructors
2. ProcessManager
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. canRun
8. killPid
9. noSuchMethod
10. run
11. runSync
12. start
13. toString
14. Operators
15. operator ==