It seems like you're looking for a Java client library to interact with the OpenAPI Specification (v2 or v3) API. The @openapitools/openapi-generator-cli package on NPM Registry provides a wrapper for OpenAPI Generator, which can generate API client libraries, server stubs, documentation, and configuration automatically given an OpenAPI Spec.

To download the Java client library for v2 or v3 API, you can use the following command:

npm install @openapitools/openapi-generator-cli

After installation, you can use the openapi-generator command to generate the Java client library. For example, to generate a client library for the v2 API:

openapi-generator generate -i path/to/openapi-spec-v2.yaml -g java -o output

Replace path/to/openapi-spec-v2.yaml with the actual path to your OpenAPI Specification file and output with the desired output directory.

Please note that you need to have Node.js installed on your system for this command to work.