[BUG] Unused JsonNullable imports

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?
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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

Reproduce the report with the linked Petstore specification and the Maven configuration using generatorName spring and version 7.0.1. Inspect the Spring generator output and existing regression tests for DTO imports; done means generated DTOs do not contain an unused JsonNullable import when nullable support is not needed.