Incorrect conversion from Openapi Spec to proto.

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
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[BUG][JAVA] Bug generating protobuf file for a json having a List of List of Transactions

Description

While generating a protobuf from an openapi spec, I am getting incorrect generation.
eg :
Input Json
{
"currentOffer":[
[
{
"date":"07/07/2022",
"amount":10000
}
]]
}

For the above schema i am getting output protobuf which shows a syntax error in the below highlighted output.

Output:
repeated array[Students] currentOffer = 123456789;

openapi-generator version

org.openapitools:openapi-generator-gradle-plugin:6.2.0

OpenAPI declaration file content or url

Steps to reproduce

Update the input json with the sample json provided above and try to generate protobuf with the json provided.

Related issues/PRs

Suggest a fix

Support can be provided for List<List>

Reproduce the protobuf generation with the nested-list sample in the issue, noting that a complete OpenAPI declaration and CLI generation details are not provided. Trace the protobuf generator's handling of nested arrays and compare the generated field with valid protobuf syntax; done means the sample generates valid output representing the nested transaction list.