[REQ] [Java][Spring] Generate a Controller per operation

[pcuriel]

Having controllers split by tags is nice, but patterns like Vertical Slicing suggest going a step further and having one Controller per endpoint.

In a similar fashion to useTags, a useOperationIds config option could be added to use the operationId to generate the interface/controller classnames.

An alternative/complementary option could be adding a x-controller-name vendor extension applicable to Operation object.

[wing328]

I've filed #17161 to meet this requirement. To give it a try, here is an example:

java -jar modules/openapi-generator-cli/target/openapi-generator-cli.jar generate -g spring -i modules/openapi-generator/src/test/resources/3_0/petstore.yaml  -o  /tmp/spring5 --openapi-normalizer SET_TAGS_TO_OPERATIONID=true --additional-properties useTags=true