Final answer:
To generate an OpenAPI specification from Java code, one must use frameworks like Springdoc-OpenAPI or Swagger.
Step-by-step explanation:
To generate an OpenAPI specification from Java code, you typically start by using annotations provided by frameworks like Springdoc-OpenAPI for Spring Boot applications or Swagger for others. These annotations are used to decorate your RESTful controllers and models.
For Spring Boot, you can include the Springdoc-OpenAPI dependency in your pom.xml or build.gradle file. Once your code is annotated, Springdoc-OpenAPI provides a web UI at /v3/api-docs by default that automatically generates and displays the OpenAPI documentation.
In case of a Swagger setup, adding the Swagger2 Maven dependency along with Swagger annotations will allow your application to produce a JSON or YAML definition of the API when you visit a designated endpoint, usually /v2/api-docs.