After updating my pubspec.yaml with my dependencies (denoted below), the flutter tool is giving me this error when I try flutter packages get
_Because every version of flutter_test from sdk depends on test 0.12.37 which depends on analyzer >=0.26.4 <0.32.0, every version of flutter_test from sdk requires analyzer >=0.26.4 <0.32.0.
And because json_serializable >=0.5.3 depends on analyzer ^0.32.0,_ flutter_test from sdk is incompatible with json_serializable >=0.5.3.
_So, because jam2018 depends on both json_serializable ^0.5.4 and flutter_test any from sdk,_ version solving failed.
pub get failed (1)

is there any way around this issue?
Which version of Flutter are you on? Did you upgrade to the latest beta (today)?
Yes, I'm pretty sure I checked my latest version of Flutter was up-to-date, but to be sure, I checked again. Flutter Doctor reported no issues, but I get a slightly different error this time in the console after running _flutter packages upgrade_.
Flutter Version info
_Flutter 0.5.1 • channel beta • https://github.com/flutter/flutter.git_
_Framework • revision c7ea3ca377 (3 weeks ago) • 2018-05-29 21:07:33 +0200_
_Engine • revision 1ed25ca7b7_
_Tools • Dart 2.0.0-dev.58.0.flutter-f981f09760_

Error Message from 'flutter packages upgrade'
_Because every version of flutter_test from sdk depends on analyzer 0.31.2-alpha.2 and json_serializable >=0.5.3 depends on analyzer ^0.32.0, flutter_test from sdk is incompatible with json_serializable >=0.5.3._
_So, because jam2018 depends on both json_serializable ^0.5.4 and flutter_test any from sdk, version solving failed._
_pub get failed (1)_

Yup. flutter_test needs to be updated to support the latest analyzer. I'd file a bug on the flutter repo...reference this issue...
will do. thanks!
just a workaround for me:
remove flutter_test, and use build_runner: "^0.8.10" for now.
and wait for flutter_test to be updated to support the latest analyzer.
dev_dependencies:
# flutter_test: # <-- remove this for now.
# sdk: flutter
build_runner: "^0.8.10" # <-- use this for now.
json_serializable: "^0.5.8"
The suggestion from @pcqpcq is a good one.
Downgrade version of JSON_serializable
Most helpful comment
just a workaround for me:
remove
flutter_test, and usebuild_runner: "^0.8.10"for now.and wait for flutter_test to be updated to support the latest analyzer.