[BUG] [MAVEN-PLUGIN] openapi specification errors reported although the spec is validated both by openapi and swagger validation tools

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?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

An API specification file validated by the openapi online tool AND by the swagger-cli validate tool without any errors, generates "false" errors when used with the openapi-generator-maven-plugin in order to generate some code. The reported errors are :

org.openapitools.codegen.SpecValidationException: There were issues with the specification. The option can be disabled via validateSpec (Maven/Gradle) or --skip-validate-spec (CLI).
 | Error count: 3, Warning count: 6
Errors: 
	-attribute components.schemas.execSdifModel.items is missing
	-attribute components.schemas.avatarAndValuesReturnModel.items is missing
	-paths.'/requests/{uuid}'. Declared path parameter uuid needs to be defined as a path parameter in path or operation level

openapi-generator version

• 6.2.1
• 6.3.0-SNAPSHOT (built by myself on 2022-12-13)

OpenAPI declaration file content or url

The same errors are raised independently of the format, yaml or json.

• swagger-original.yaml
• swagger-original.json

Generation Details

All the details with the stack trace :

[INFO] 
VERBOSE MODE: ON. Additional debug options are injected
 - [debugOpenAPI] prints the OpenAPI specification as interpreted by the codegen
 - [debugModels] prints models passed to the template engine
 - [debugOperations] prints operations passed to the template engine
 - [debugSupportingFiles] prints additional data passed to the template engine
[INFO] [deprecated] inheritance without use of 'discriminator.propertyName' has been deprecated in the 5.x release. Composed schema name: null. Title: null
[WARNING] /home/rhzj7430/dev/thingin/thingin-one-poc/backend/src/main/resources/swagger-original.yaml [0:0]: unexpected error in Open-API generation
org.openapitools.codegen.SpecValidationException: There were issues with the specification. The option can be disabled via validateSpec (Maven/Gradle) or --skip-validate-spec (CLI).
 | Error count: 3, Warning count: 6
Errors: 
	-attribute components.schemas.execSdifModel.items is missing
	-attribute components.schemas.avatarAndValuesReturnModel.items is missing
	-paths.'/requests/{uuid}'. Declared path parameter uuid needs to be defined as a path parameter in path or operation level
Warnings: 
	-attribute components.schemas.execSdifModel.items is missing
	-attribute components.schemas.avatarAndValuesReturnModel.items is missing
	-paths.'/requests/{uuid}'. Declared path parameter uuid needs to be defined as a path parameter in path or operation level

    at org.openapitools.codegen.config.CodegenConfigurator.toContext (CodegenConfigurator.java:604)
    at org.openapitools.codegen.config.CodegenConfigurator.toClientOptInput (CodegenConfigurator.java:631)
    at org.openapitools.codegen.plugin.CodeGenMojo.execute (CodeGenMojo.java:798)
    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.DirectMethodHandleAccessor.invoke (DirectMethodHandleAccessor.java:104)
    at java.lang.reflect.Method.invoke (Method.java:578)
    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)
    at org.codehaus.classworlds.Launcher.main (Launcher.java:47)

The plugin configuration is the following :

            <plugin>
                <groupId>org.openapitools</groupId>
                <artifactId>openapi-generator-maven-plugin</artifactId>
                <version>${openapi-generator-maven-plugin.version}</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>generate</goal>
                        </goals>
                        <configuration>
                            <verbose>true</verbose>
                            <skipValidateSpec>false</skipValidateSpec>
                            <inputSpec>${project.basedir}/src/main/resources/swagger-original.yaml</inputSpec>
                            <generatorName>java-vertx-web</generatorName>
                            <output>${project.build.outputDirectory}/generated-sources/java/</output>
                            <apiPackage>com.orange.thingin.api</apiPackage>
                            <modelPackage>com.orange.thingin.api.model</modelPackage>
                            <invokerPackage>com.orange.thingin</invokerPackage>
                        </configuration>
                    </execution>
                </executions>
            </plugin>

Steps to reproduce

just try to run the maven plugin with the given specification file.

Related issues/PRs

Suggest a fix

Start at CodegenConfigurator.toContext and CodeGenMojo.execute, then reproduce the Maven plugin run with the linked swagger-original.yaml or JSON specification. Compare the generator's validation output with the OpenAPI and swagger-cli results; done means the reported validation behavior is consistent with the supplied specification and the reproduction is covered by the relevant generator checks.