[BUG][native][apache-httpclient] Generated code contains warnings in ApiClient

[welandaz]

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?

Description

If you add -Xlint:all, -Werror to java compiler options, you will get error on any open-api specification.

• When native as a library is used, the generator generates code with [this-escape] possible 'this' escape before subclass is fully initialized warnings in ApiClient.
• When apache-httpclient as a library is used, the generator generates code with [rawtypes] found raw type: Collection warnings in ApiClient.

openapi-generator version

7.4.0

OpenAPI declaration file content or url

https://github.com/OpenAPITools/openapi-generator/blob/1105759a6f20edac389fa547359c7d5e6c4f9ac8/modules/openapi-generator-gradle-plugin/samples/local-spec/petstore-v3.0.yaml

Generation Details

Steps to reproduce

jdk: Oracle OpenJDK 21.0.1
gradle: 8.7
open-api generator plugin: 7.4.0

plugins {
    id("java")
    id("org.openapi.generator") version "7.4.0"
}

group = "com.test"
version = "1.0"

repositories {
    mavenCentral()
}

dependencies {
    implementation("jakarta.annotation:jakarta.annotation-api:3.0.0")

    implementation("org.openapitools:jackson-databind-nullable:0.2.6")
    implementation("com.fasterxml.jackson.core:jackson-annotations:2.16.1")
    implementation("com.fasterxml.jackson.core:jackson-core:2.16.1")
    implementation("com.fasterxml.jackson.core:jackson-databind:2.16.1")
    implementation("com.fasterxml.jackson.jaxrs:jackson-jaxrs-json-provider:2.13.4")
    implementation("com.fasterxml.jackson.datatype:jackson-datatype-jsr310:2.17.0")

    implementation("javax.annotation:javax.annotation-api:1.3.2")

    implementation("org.apache.httpcomponents.client5:httpclient5:5.4-alpha2")

    testImplementation(platform("org.junit:junit-bom:5.9.1"))
    testImplementation("org.junit.jupiter:junit-jupiter")
}

sourceSets {
    named("main") {
        java {
            srcDir("$buildDir/java/src/main/java")
        }
    }
}

tasks.test {
    useJUnitPlatform()
}

openApiGenerate {
    generatorName = "java"
    inputSpec = "$projectDir/src/main/resources/petstore-v3.0.yaml"
    outputDir = "$buildDir/java"
    apiPackage = "org.openapitools.example.api"
    invokerPackage = "org.openapitools.example.invoker"
    modelPackage = "org.openapitools.example.model"
    configOptions.putAll(mapOf(
        "library" to "apache-httpclient", // change to native for other warnings
        "dateLibrary" to "java8",
        "serializationLibrary" to "jackson",
        "useJakartaEe" to "true",
        "hideGenerationTimestamp" to "true",
        "openApiNullable" to "false",
        "useBeanValidation" to "false",
        "disallowAdditionalPropertiesIfNotPresent" to "false",
        "containerDefaultToNull" to "true",
    ))
}

tasks.withType<JavaCompile> {
    options.compilerArgs.addAll(listOf("-Xlint:all", "-Werror"))
}

Related issues/PRs

#17475

Suggest a fix

• native library: Change the implementation of affected methods with [this-escape] warnings
• apache-httpclient library: Don't use raw type with Collection object (reimplement with generics if possible)

[ainurabdrashitov]

Looks similar to the #17475

[welandaz]

Resolved by #20466