[BUG][Java][native] Regression Native library generator cannot handle model with unique enum field

Description

When updating the gradle plugin from version 6.2.1 to 7.0.1 the generated code no longer compiles.
relevant stuff from the schema is:

          "operators": {
            "items": {
              "enum": [
                "EQUALS",
                "NOT_EQUALS",
                "GREATER_OR_EQUAL",
                "GREATER",
                "LESSER_OR_EQUAL",
                "LESSER",
                "STARTS_WITH",
                "NOT_STARTS_WITH",
                "ENDS_WITH",
                "NOT_ENDS_WITH",
                "EMPTY",
                "NOT_EMPTY",
                "CONTAINS",
                "NOT_CONTAINS"
              ],
              "type": "string"
            },
            "type": "array",
            "uniqueItems": true
          },

This is from a model definition.
The generated code that does not compile looks like this:

    // add `operators` to the URL query string
    if (getOperators() != null) {
      int i = 0;
      for (String _item : getOperators()) {
        joiner.add(String.format("%soperators%s%s=%s", prefix, suffix,
            "".equals(suffix) ? "" : String.format("%s%d%s", containerPrefix, i, containerSuffix),
            URLEncoder.encode(String.valueOf(_item), StandardCharsets.UTF_8).replaceAll("\\+", "%20")));
      }
      i++;
    }

However get operators looks like this:

  public Set<OperatorsEnum> getOperators() {
    return operators;
  }

This obvieusly does not compile since OperatorsEnum != String

This entire thing only exists in context of toUrlQueryString which is very confusing as I use JSON for this model
and never URLQuery. My editor also tells me that the new method toUrlQueryString is never used.

When manually chaning the defition of the model to be "uniqueItems": false the generated code does compile.
This is however not an option for me as I am not the "source" of the openapi files it take them from another vendor.

openapi-generator version

It is a regression!

OpenAPI declaration file content or url

Generation Details

tasks.register("genV2") {
validateSpec.set(false)
generatorName.set("java")
inputSpec.set("$rootDir/src/main/resources/redacted.json")
library.set("native")
outputDir.set("$rootDir/generated/v2")
invokerPackage.set("redacted")
modelPackage.set("redacted")
apiPackage.set("redacted")
configOptions.put("dateLibrary", "java8")
configOptions.put("serializableModel", "true")
configOptions.put("authorization", "basicAuth")
configOptions.put("useGenericResponse", "true")
configOptions.put("artifactId", "tmp")
configOptions.put("groupId", "redacted")
configOptions.put("basePackage", "redacted")
configOptions.put("configPackage", "redacted")
configOptions.put("useRuntimeException", "true")
configOptions.put("hideGenerationTimestamp", "true")
}

Steps to reproduce

See above

Related issues/PRs

None to my knowledge

Suggest a fix

Do not generate the toUrlQueryString or let me have a configOptions in my build script so i can disable this generation. I dont need it.

EDIT: i just realized that such an option already exists and solves my problem adding:
configOptions.put("supportUrlQuery", "false")
makes the compile error go away. Still for those that do need this option it should still be fixed.

Reproduce the issue with the Gradle genV2 task using the Java generator's native library and a schema containing a unique enum array. Inspect the generated model's toUrlQueryString method and the handling of getOperators(); done means generated code compiles while preserving URL query support for the set of enum values.