[dart-dio] Fixes errors when deserializing primitive return types

[josh-burton]

Fixes errors when primitive return types are attempted to be deserialized as json

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CC: @ircecho @swipesight @jaumard @amondnet

[kuhnroyal]

@josh-burton This needs to be {{{returnType}}} or it will break with primitive lists.

[josh-burton]

@kuhnroyal whats the difference between {{returnType}} and {{{returnType}}}? (has always confused me)

[kuhnroyal]

Afaik 2 braces perform HTML escaping and won't work for types like List<String> that's why you mostly see 3 braces for type definitions.

Can you rebase the branch and see if it goes green? So many small fixes for Dart but they don't get merged.

[kuhnroyal]

@josh-burton What is missing to get this merged?

[josh-burton]

@kuhnroyal I'm still waiting on this to be reviewed. CC @ircecho @swipesight @jaumard @amondnet

[kuhnroyal]

@josh-burton I fixed the same problem in #8025 but your fix makes more sense so I will rebase once this here is merged.

[kuhnroyal]

My branch with integration test got merged first.
You can now run integration tests with ./mvnw integration-test -f samples/client/petstore/dart-dio/pom.xml

[kuhnroyal]

@josh-burton Can you rebase this please? We are currently merging a lot of PRs so I am sure we can get this in.

[kuhnroyal]

There is something wrong here when these types get generated - this was fixed in 7fae4ab

[josh-burton]

yep just fixing that :)

[kuhnroyal]

You need to delete the 4 old files manually.

[wing328]

CircleCI failure not related to this change.