* Add flutter_lints package
* Use key in widget constructors
lint: use_key_in_widget_constructors
* Unnecessary new keyword
lint: unnecessary_new
* Prefer const with constant constructors
* Exclude protobuf files from analyzer
* Private field could be final
* Annotate overridden members
* Use initializing formals when possible
* Don't access members with `this` unless avoiding shadowing
* Prefer is! operator
* Use isEmpty instead of length
* Use collection literals when possible
* Revert comment changes
* Cleaner null testing
* Misc fixes
* Avoid using `forEach` with a function literal
* Prefer `final` over `var` where applicable
* Enforce stricter type-checking
* Ignore VS Code files
* Flutter format
* Prefer using lowerCamelCase for constant names
* flutter format -l 100
* Disable `avoid_print` for examples
* Slight improvements to example
Should solve lint error: no_logic_in_create_state
Hiroshi Horie