[BUG] [JAVA] Array of oneOf should be possible to be empty

Description

When using oneOf for an array it generates in a way that array of single value can not be empy. If you leave out the oneOf and have an array of just strings it can be empty.

if (instance instanceof List) {
                List<?> list = (List)instance;
                if (list.get(0) instanceof sv) {
                    super.setActualInstance(instance);
                    return;
                }
            }

openapi-generator version

7.6.0 -snapshot default library

OpenAPI declaration file content or url

    mv:
      oneOf:
        - $ref: "#/components/schemas/sv"
        - type: array
          items:
            $ref: "#/components/schemas/sv"

    sv:
      oneOf:
        - type: number
          format: double
        - type: string 

Generation Details

Steps to reproduce

Related issues/PRs

Suggest a fix

Allow it to be empty

Start by reproducing the OpenAPI schema from the issue with openapi-generator 7.6.0-SNAPSHOT using the default library, then inspect the generated Java validation around the shown List and oneOf handling. Done means an empty array is accepted while the existing single-value and non-empty array cases remain valid.