Fix Kotlin codegen for enum with int items (issue #15204)

[exviva]

When an array property has enum integer items, the kotlin codegen would generate invalid code, e.g.:

    /**
     * 
     *
     * Values: _0,_1,_2,_3,_4,_5,_6
     */
    enum class DaysOfWeek(val value: kotlin.String) { // <---- value is of type String
        @JsonProperty(value = "0") _0(0), // <---- but Ints are being passed to constructor
        @JsonProperty(value = "1") _1(1),
        @JsonProperty(value = "2") _2(2),
        @JsonProperty(value = "3") _3(3),
        @JsonProperty(value = "4") _4(4),
        @JsonProperty(value = "5") _5(5),
        @JsonProperty(value = "6") _6(6);
    }

With the fix, the code is generated correctly:

    /**
     *
     *
     * Values: _0,_1,_2,_3,_4,_5,_6
     */
    enum class DaysOfWeek(val value: kotlin.Int) {
        @JsonProperty(value = "0") _0(0),
        @JsonProperty(value = "1") _1(1),
        @JsonProperty(value = "2") _2(2),
        @JsonProperty(value = "3") _3(3),
        @JsonProperty(value = "4") _4(4),
        @JsonProperty(value = "5") _5(5),
        @JsonProperty(value = "6") _6(6);
    }

I was following the Java codegen.

Fixes #15204.

@karismann @Zomzog @andrewemery @4brunu @stefankoppier @e5l

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[wing328]

Thanks for the PR but your commit (as shown in the Commits tab) is not linked to your Github account, which means this PR won't count as your contribution in https://github.com/OpenAPITools/openapi-generator/graphs/contributors.

Let me know if you need help fixing it.

Ref: https://github.com/OpenAPITools/openapi-generator/wiki/FAQ#how-can-i-update-commits-that-are-not-linked-to-my-github-account

[exviva]

@wing328 thanks for the review! You're right, I was on my work account -- amended.

[wing328]

lgtm. let's give it a try

thanks for the contribution

[exviva]

lgtm. let's give it a try

Thanks @wing328, appreciate it! Do we have an ETA for a 7.18.0 release?

[wing328]

please refer to milestones

[wing328]

FYI. Merged #22336 to add a test covering this moving forward