[Java] [Spring] code style improvement

[artemitin]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

In Java Spring generator: Inconsistent and nonconventional use/absence of spaces in method signatures in generated *Api.java.

Generated:

default ResponseEntity<Void> addPet(@ApiParam(value = "Pet object that needs to be added to the store" ,required=true )  @Valid @RequestBody Pet body) {
        return new ResponseEntity<>(HttpStatus.NOT_IMPLEMENTED);
    }

Should be:

default ResponseEntity<Void> addPet(@ApiParam(value = "Pet object that needs to be added to the store", required = true) @Valid @RequestBody Pet body) {
        return new ResponseEntity<>(HttpStatus.NOT_IMPLEMENTED);
    }

openapi-generator version

5.2.1, master

Generation Details

gradle task config, using downloaded https://petstore.swagger.io/v2/swagger.json

openApiGenerate {
    generatorName = "spring"
    inputSpec = "$projectDir/src/main/resources/swagger.json"

Steps to reproduce

generate and see *Api.java classes

Suggest a fix

adjust templates in src/main/resources/JavaSpring