[BUG] Swagger parser has updated array schema for openapi 3.1.0

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Description

This issue is for tracking perspective since affect lot of places for different generators
When swagger-parser process schema for OpenAPI v3.0.0 it represents arrays via ArraySchema class. openapi-generator highly rely on this type to identify whether type is array or not - https://github.com/OpenAPITools/openapi-generator/blob/1b344597bf642108c95bf98ad8f9f44b7dd568e0/modules/openapi-generator/src/main/java/org/openapitools/codegen/utils/ModelUtils.java#L538

During investigation of this issue I've found that in openapi 3.1.0 arrays are represented as JsonSchema therefore generator don't determine type properly -

1. https://github.com/swagger-api/swagger-parser/blob/c0c434bf1c0189e9a770e31c50d4bc19bcf2dd08/modules/swagger-parser-v3/src/main/java/io/swagger/v3/parser/util/OpenAPIDeserializer.java#L2635
2. https://github.com/swagger-api/swagger-parser/blob/c0c434bf1c0189e9a770e31c50d4bc19bcf2dd08/modules/swagger-parser-v3/src/main/java/io/swagger/v3/parser/util/OpenAPIDeserializer.java#L3815

FYI @wing328 (2015/07) ❤️
@jimschubert (2016/05) ❤️
@cbornet (2016/05)
@jmini (2018/04) ❤️
@etherealjoy (2019/06)
@spacether (2020/05) ❤️

Start with ModelUtils.java around line 538, then inspect the OpenAPIDeserializer.java locations cited for OpenAPI 3.1 array handling. Compare how ArraySchema is recognized for OpenAPI 3.0 with how JsonSchema represents arrays in 3.1; done means the generator identifies these schemas as arrays across the affected generators.