使用OpenAPI生成Micronaut POST端点时构建失败求助

使用openapi-generator结合Micronaut开发时，构建抛出NullPointerException：

Cannot invoke "String.equals(Object)" because the return value of "io.swagger.v3.oas.models.parameters.Parameter.getIn()" is null

完整报错堆栈：

warning: Error:
  Cannot invoke "String.equals(Object)" because the return value of "io.swagger.v3.oas.models.parameters.Parameter.getIn()" is null
  java.lang.NullPointerException: Cannot invoke "String.equals(Object)" because the return value of "io.swagger.v3.oas.models.parameters.Parameter.getIn()" is null
    at io.micronaut.openapi.visitor.SchemaUtils.mergeOperations(SchemaUtils.java:324)
    ...（完整堆栈省略）

相关配置及代码如下：

OpenAPI规范 #

openapi: 3.0.0
info:
  version: 1.0.0
  title: Ninja
tags:
  - name: rentals
paths:
  /rentals:
    post:
      tags:
        - rentals
      operationId: create
      requestBody:
        content:
          "application/json":
            schema:
              $ref: "#/components/schemas/RentalInfo"
      responses:
        "201":
          description: Created
          content:
            "application/json":
              schema:
                $ref: "#/components/schemas/RentalInfo"
        "400":
          description: Bad Request
components:
  schemas:
    RentalInfo:
      type: object
      properties:
        uuid: { type: string }
        name: { type: string }
      required: [ "uuid", "name" ]

API实现代码 #

@Controller
class Rentals implements RentalsApi {

    @Override
    public HttpResponse<RentalInfo> create(final RentalInfo rentalInfo) {
        return HttpResponse.created(rentalInfo);
    }
}

Gradle配置 #

plugins {
    id("groovy") 
    id("com.github.johnrengelman.shadow") version "8.1.1"
    id("io.micronaut.application") version "4.0.4"
    id("io.micronaut.aot") version "4.0.4"
    id("io.micronaut.openapi") version "4.0.4"
}
version = "0.1"
group = "dev.jjrz"
repositories {
    mavenCentral()
}
dependencies {
    annotationProcessor("io.micronaut:micronaut-http-validation")
    annotationProcessor("io.micronaut.openapi:micronaut-openapi")
    annotationProcessor("io.micronaut.serde:micronaut-serde-processor")
    implementation("io.micronaut.security:micronaut-security")
    implementation("io.micronaut.serde:micronaut-serde-jackson")
    implementation("io.swagger.core.v3:swagger-annotations")
    compileOnly("io.micronaut:micronaut-http-client")
    runtimeOnly("ch.qos.logback:logback-classic")
    testImplementation("io.micronaut:micronaut-http-client")
}
application {
    mainClass.set("dev.jjrz.ninja2.Application")
}
java {
    sourceCompatibility = JavaVersion.toVersion("17")
    targetCompatibility = JavaVersion.toVersion("17")
}
graalvmNative.toolchainDetection = false
micronaut {
    runtime("netty")
    testRuntime("spock2")
    processing {
        incremental(true)
        annotations("dev.jjrz.*")
    }
    aot {
        optimizeServiceLoading = false
        convertYamlToJava = false
        precomputeOperations = true
        cacheEnvironment = true
        optimizeClassLoading = true
        deduceEnvironment = true
        optimizeNetty = true
    }
    openapi {
        server(file("src/main/resources/ninja2-api.yml")) {
            apiPackageName = "dev.jjrz.ninja2.api"
            modelPackageName = "dev.jjrz.ninja2.model"
            useReactive = false
            useAuth = true
        }
    }
}

已知移除请求体或去掉@Controller注解时构建可正常通过，但@Controller是端点实现必需的，需解决该问题以实现POST请求的正常生成。

给请求体参数添加@Body注解 #

在API实现的create方法参数上显式标记@Body注解，明确该参数对应请求体，避免Micronaut处理元数据时将其误判为无in属性的参数：

@Controller
class Rentals implements RentalsApi {

    @Override
    public HttpResponse<RentalInfo> create(@Body final RentalInfo rentalInfo) {
        return HttpResponse.created(rentalInfo);
    }
}

升级Micronaut OpenAPI插件版本 #

该NullPointerException是Micronaut OpenAPI插件4.0.x版本的已知bug，升级到4.1.0及以上版本可修复。修改Gradle配置中的插件版本：

plugins {
    // 保留其他插件配置
    id("io.micronaut.openapi") version "4.1.0"
}

同时同步更新依赖中的注解处理器版本，确保与插件版本一致：

dependencies {
    // 保留其他依赖配置
    annotationProcessor("io.micronaut.openapi:micronaut-openapi:4.1.0")
}

在OpenAPI规范中显式标记请求体为必填 #

在OpenAPI的requestBody节点添加required: true，帮助插件更准确识别请求体参数：

paths:
  /rentals:
    post:
      # 保留其他配置
      requestBody:
        required: true
        content:
          "application/json":
            schema:
              $ref: "#/components/schemas/RentalInfo"

内容的提问来源于stack exchange，提问作者jjrz