To download the vnu.jar file for Nu Html Checker, you can use the following command in your Java project:

wget https://registry.npmjs.org/vnu-jar/-/vnu.jar

However, since you mentioned downloading a Vector HD Product Recipe, I'm assuming you're looking for the @upstash/vector package.

To download the @upstash/vector package in Java, you can use the following command:

npm install @upstash/vector

This will download the jar file and add it to your project's dependencies.

If you want to generate an API client library (SDK) for Vector HD using OpenAPI Generator, you can use the following command:

npm install -D @openapitools/openapi-generator-cli
openapi-generator generate -i path/to/your/openapi-spec.json -g java -o output-path

Please replace path/to/your/openapi-spec.json with the actual path to your OpenAPI specification file, and output-path with the desired output directory.