[@nestjs/swagger v7] oneOf doesn't work as expected

[karlismelderis-mckinsey]

Did you read the migration guide?

• I have read the whole migration guide

Is there an existing issue that is already proposing this?

• I have searched the existing issues

Potential Commit/PR that introduced the regression

No response

Versions

6 -> 7.4.0

Describe the regression

@ApiProperty({
        type: undefined,
        oneOf: [
          { type: 'array', items: { type: 'string' } },
          { type: 'array', items: { type: 'number' } },
          { type: 'array', items: { type: 'boolean' } },
        ],
        description: API_DESCRIPTION,
      })
values: string[] | number[] | boolean[]

this configuration used to produce this schema in v6

"values": {
  "oneOf": [
    {
      "type": "array",
      "items": {
        "type": "string"
      }
    },
    {
      "type": "array",
      "items": {
        "type": "number"
      }
    },
    {
      "type": "array",
      "items": {
        "type": "boolean"
      }
    }
  ]
}

in v7 for some reason type: array is added and oneOf suddenly defines items not schema of "values"

Minimum reproduction code

@ApiProperty({
        type: undefined,
        oneOf: [
          { type: 'array', items: { type: 'string' } },
          { type: 'array', items: { type: 'number' } },
          { type: 'array', items: { type: 'boolean' } },
        ],
        description: API_DESCRIPTION,
      })
values: string[] | number[] | boolean[]

Expected behavior

I expect to see this schema to be generated:

"values": {
  "oneOf": [
    {
      "type": "array",
      "items": {
        "type": "string"
      }
    },
    {
      "type": "array",
      "items": {
        "type": "number"
      }
    },
    {
      "type": "array",
      "items": {
        "type": "boolean"
      }
    }
  ]
}

Other

No response

[karlismelderis-mckinsey]

I think I found a workaround

type Values = string[] | number[] | boolean[]

@ApiProperty({
        type: undefined,
        oneOf: [
          { type: 'array', items: { type: 'string' } },
          { type: 'array', items: { type: 'number' } },
          { type: 'array', items: { type: 'boolean' } },
        ],
        description: API_DESCRIPTION,
      })
values: Values

it will do for us but behaviour is unexpected nevertheless