[BUG] Unused JsonNullable imports

[Haarolean]

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

An import import org.openapitools.jackson.nullable.JsonNullable; is being added to DTOs despite they're never used.
It's solvable by adding <openApiNullable>false</openApiNullable> config property but I believe the import shouldn't be there if it's unused.

openapi-generator version

7.0.1. Might be a regression of #2901

OpenAPI declaration file content or url

https://gist.github.com/Haarolean/8a9b07f74544c7e45d553ff33798ed8c (swagger petstore)

Generation Details

maven,

    <build>
        <plugins>
            <plugin>
                <groupId>org.openapitools</groupId>
                <artifactId>openapi-generator-maven-plugin</artifactId>
                <version>7.0.1</version>
                <executions>
                    <execution>
                        <id>interfaces</id>
                        <goals>
                            <goal>generate</goal>
                        </goals>
                        <configuration>
                            <inputSpec>${project.basedir}/src/main/resources/api.yaml</inputSpec>
                            <output>${project.build.directory}/generated-sources/api</output>
                            <generatorName>spring</generatorName>
                            <modelNameSuffix>DTO</modelNameSuffix>
                            <configOptions>
                                <modelPackage>lol.memelord.kapybro.api.dto</modelPackage>
                                <apiPackage>lol.memelord.kapybro.api.api</apiPackage>
                                <sourceFolder>test</sourceFolder>
                                <interfaceOnly>true</interfaceOnly>
                                <skipDefaultInterface>true</skipDefaultInterface>
                                <useBeanValidation>true</useBeanValidation>
                                <useTags>true</useTags>
                                <useSpringBoot3>true</useSpringBoot3>
                                <dateLibrary>java8</dateLibrary>
<!--                                <useOpenApiNullable>false</useOpenApiNullable>-->
<!--                                <openApiNullable>false</openApiNullable>-->
                            </configOptions>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

Steps to reproduce

1. build the spec

Related issues/PRs

#2901

Suggest a fix

[wing328]

It's solvable by adding false config property but I believe the import shouldn't be there if it's unused.

@Haarolean right. Do you mind contributing a PR to remove the import when openApiNullableis is disabled?