Support for modelPropertyNaming, other then camelCase, in the Dart language

[manuelgomes2]

… Dart language options.

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Description of the PR

(details of the change, additional tests that have been done, reference to the issue for tracking, etc)

[lingster]

Hi, just wondering if there are any updates for this PR and if it will be merged into master? I was about to submit a similar PR to solve this issue for the dart code generator too! Ling

[yk-theapps]

someone, please help to resolve this conflict

[HugoMario]

@yukayeung on it

[HugoMario]

hello guys, i just resolved conflict but PR is failing on this assertion:
https://github.com/swagger-api/swagger-codegen/blob/master/modules/swagger-codegen/src/test/java/io/swagger/codegen/dart/DartModelEnumTest.java#L83

java.lang.AssertionError: expected [Sample] but found [sample]
	at io.swagger.codegen.dart.DartModelEnumTest.overrideEnumTest(DartModelEnumTest.java:83)

@lingster @yukayeung , i'm not familiar with dart, so can you please let me know if the test is ok failing here or should be changed?

[yk-theapps]

I'm quite a beginner on Dart too. but In Dart, the class naming convention is followed UpperCamelCase too. if code gent DartModelEnum test is case sensitive. it should be changed.
Let seek advice from @lingster since he did helping to do similar PR for this.

[lingster]

@HugoMario This PR allows users to change the naming of the modelProperty. It's been defaulted to camelCase as per line: 38 here: e08e0eb

I think the tests might pass if you amend this to be:
protected String modelPropertyNaming = CodegenConstants.MODEL_PROPERTY_NAMING_TYPE.PascalCase.name();