...

java -jar swagger-codegen-cli.jar generate \
  -i openapi.json \
  -o apiclient \
  -l java

OpenAPI Generator

OpenAPI Generator is similar to Swagger Codegen. Most of the options are identical. It supports a slightly different set of languages and libraries, and generates slightly different style of code.

...

java -jar openapi-generator-cli.jar generate \
  -i openapi.json \
  -o apiclient \
  -g java \
  --skip-validate-spec