[BUG] [Java] [Spring] Redundant "import java.time.OffsetDateTime" when using typeMappings

Description

Specifying typeMapping for "string+date-time" doesn't remove the import of OffsetDateTime.

<plugin>
    <groupId>org.openapitools</groupId>
    <artifactId>openapi-generator-maven-plugin</artifactId>
    <executions>
        <execution>
            <configuration>
                <typeMappings>
                    <typeMapping>string+date-time=LocalDateTime</typeMapping>
                </typeMappings>
                <importMappings>
                    <importMapping>LocalDateTime=java.time.LocalDateTime</importMapping>
                </importMappings>
            </configuration>
        </execution>
    </executions>
    <-- Other configs -->
</plugin>

openapi-generator version

openapi-generator-maven-plugin version 6.0.1

OpenAPI declaration file content or url

components:
  schemas:
    Foo:
      type: object
      properties:
        createdAt:
          type: string
          format: date-time

Steps to reproduce

Use the Open API with the typeMapping and importMapping above

Suggest a fix

Remove the fixed OffsetDateTime import at https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/JavaSpring/model.mustache#L13

Start with modules/openapi-generator/src/main/resources/JavaSpring/model.mustache, especially the fixed import mentioned in the issue. Reproduce generation with the shown typeMapping and importMapping, then verify the generated Spring model no longer includes the redundant OffsetDateTime import while retaining the LocalDateTime mapping.