openapi-generator-maven-plugin upgrade openapi spec to 3.1.0

I am using plugin openapi-generator-maven-plugin in version 5.3.1.

Upgrading openapi spec from 3.0.3 to 3.1.0 causes generation phase errors:

Spec sample:

{
  "openapi": "3.1.0",
  "info": {
    "title": "Spec sample",
    "version": "1.0.0"
  },
  "paths": {
    "/users": {
      "get": {
        "responses": {
          "200": {}
        }
      }
    }
  }
}

plugin error:

[INFO] Output directory ((removed)targetgenerated-sourcesopenapi) does not exist, or is inaccessible. No file (.openapi-generator-igno
re) will be evaluated.
[WARNING] (removed).json [0:0]: unexpected error in Open-API generation
java.lang.RuntimeException: Issues with the OpenAPI input. Possible causes: invalid/missing spec, malformed JSON/YAML files, etc.
    at org.openapitools.codegen.DefaultGenerator.generate (DefaultGenerator.java:865)
    at org.openapitools.codegen.plugin.CodeGenMojo.execute (CodeGenMojo.java:754)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:193)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
[ERROR]
java.lang.RuntimeException: Issues with the OpenAPI input. Possible causes: invalid/missing spec, malformed JSON/YAML files, etc.
    at org.openapitools.codegen.DefaultGenerator.generate (DefaultGenerator.java:865)
    at org.openapitools.codegen.plugin.CodeGenMojo.execute (CodeGenMojo.java:754)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:193)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)

Previous version of openapi works fine..

{
  "openapi": "3.0.3",
  "info": {
    "title": "Spec sample",
    "version": "1.0.0"
  },
  "paths": {
    "/users": {
      "get": {
        "responses": {
          "200": {}
        }
      }
    }
  }
}

I couldn’t find information if plugin supports that version of spec, but error message is very vauge.

How to use openapi-generator-maven-plugin with spec 3.1.0?

Answer

As of July 2022, OpenAPI Generator does not support OpenAPI 3.1 yet. Follow this issue for updates:
https://github.com/OpenAPITools/openapi-generator/issues/9083