[Kotlin] Fix parse error when using custom field names with @Json

[keijumt]

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Description of the PR

To parse a model using custom fields, KotlinJsonAdapterFactory needs to be added to moshi's Adapter.

• Fix parse error when using custom field names with @JSON
• Fix to use isEmpty method for string length verification

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

[karismann]

LGTM

[ackintosh]

I just reran the CI job. > Shippable TIMEOUT

[karismann]

should fix #2961

[keijumt]

@karismann
#2961 is solved by adding KotlinJsonAdapterFactory to adapter of Moshi.
I think that there is no problem because I added KotlinJsonAdapterFactory after adding CustomTypeAdapter, What do you think of it?

[karismann]

@karismann
#2961 is solved by adding KotlinJsonAdapterFactory to adapter of Moshi.
I think that there is no problem because I added KotlinJsonAdapterFactory after adding CustomTypeAdapter, What do you think of it?

i think your change is ok and fix #2961 , that's what i would mean

[keijumt]

@karismann
I understand, Thanks.

[wing328]

@keijumt thanks again for your contribution, which has been included in the v4.0.1 release (https://twitter.com/oas_generator/status/1135534738658062336)