[BUG][JAVA] Description

[IkeOTL]

Description

When using the "java" generator with the "native" library config the generated "ApiClient" class has an import with missing package.

openapi-generator version

4.3.1

OpenAPI declaration file content or url

Gradle plugin task

task buildApiClient(type: org.openapitools.generator.gradle.plugin.tasks.GenerateTask){
    generatorName = "java"
    inputSpec = "$projectDir/api-spec.yaml".toString()
    outputDir = "$projectDir/generated/".toString()
    apiPackage = "com.a.b.c.openapi.client.controllers"
    modelPackage = "com.a.b.c.openapi.client.models"
    invokerPackage = "com.a.b.c.openapi.client.client"
    configOptions = [
        dateLibrary: "java8",
        interfaceOnly: "true",
        library: "native",
        artifactId: "api-server-client"
    ]
}

Steps to reproduce

Run gradle task 'buildApiClient'

Suggested fix

Add the following missing dependency to the build.gradle on project generation:
compile group: "org.openapitools", name: "jackson-databind-nullable", version: "0.2.1"