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

openapi-generator version

4.3.1
and also reproduced on master

Additional:
os: macOS
os version: 11.2 (20D64)
openjdk version "1.8.0_265"
OpenJDK Runtime Environment (AdoptOpenJDK)(build 1.8.0_265-b01)
OpenJDK 64-Bit Server VM (AdoptOpenJDK)(build 25.265-b01, mixed mode)

OpenAPI declaration file content or url

https://raw.githubusercontent.com/OpenAPITools/openapi-generator/master/modules/openapi-generator/src/test/resources/3_0/petstore.yaml

Generation Details

When I specify generate --api-name-suffix MySuffix (doc) and use spring generator I expect that the java interfaces in default api package org.openapitools.api will contain MySuffix in the names similar to --model-name-suffix parameter but for models. But I see just default Api suffix.

Actual:

ls ~/Documents/openapi-generated/spring/src/main/java/org/openapitools/api
ApiUtil.java
PetApi.java
PetApiController.java
StoreApi.java
StoreApiController.java
UserApi.java
UserApiController.java

Expected:

ApiUtil.java
PetMySuffix.java
PetMySuffixController.java
StoreMySuffix.java
StoreMySuffixController.java
UserMySuffix.java
UserMySuffixController.java

Steps to reproduce

Took master branch as in example or install 4.3.1 and run:

java -jar modules/openapi-generator-cli/target/openapi-generator-cli.jar generate \
--api-name-suffix MySuffix \
-g spring \
-i https://raw.githubusercontent.com/OpenAPITools/openapi-generator/master/modules/openapi-generator/src/test/resources/3_0/petstore.yaml \
-o ~/Documents/openapi-generated/spring

then
ls ~/Documents/openapi-generated/spring/src/main/java/org/openapitools/api

Related issues/PRs

No similar opened issues. No similar closed issues for spring.
Something similar but for Dart #5409 But let me emphasise that --model-name-suffix works well with spring.

Suggest a fix