[QUESTION] [JAVA] possible bug openapi-generator-maven-plugin handling of different discriminator values mapping to the same schema

[IgorMaj]

Hello, I have the following problem as of 7.14.0, which is also present on the latest master. The issue is not present in 7.13.0 and earlier.

Here is my snippet:

      responses:
        '200':
          description: "List of all the objects."
          content:
            application/json:
              schema:
                type: array
                items:
                  oneOf:
                    - $ref: '#/components/schemas/TypeA'
                    - $ref: '#/components/schemas/TypeB'
                  discriminator:
                    propertyName: discriminatorProperty
                    mapping:
                      ONE: '#/components/schemas/TypeA'
                      TWO: '#/components/schemas/TypeB'
                      THREE: '#/components/schemas/TypeB'
                      FOUR: '#/components/schemas/TypeB'
                      FIVE: '#/components/schemas/TypeB'

When trying to generate openapi controllers and api objects I get the following error:

java.lang.IllegalStateException: Duplicate key #/components/schemas/TypeB (attempted merging values TWO and THREE)
    at java.util.stream.Collectors.duplicateKeyException (Collectors.java:135)
    at java.util.stream.Collectors.lambda$uniqKeysMapAccumulator$1 (Collectors.java:182)
    at java.util.stream.ReduceOps$3ReducingSink.accept (ReduceOps.java:169)
    at java.util.Iterator.forEachRemaining (Iterator.java:133)
    at java.util.Spliterators$IteratorSpliterator.forEachRemaining (Spliterators.java:1939)
    at java.util.stream.AbstractPipeline.copyInto (AbstractPipeline.java:509)
    at java.util.stream.AbstractPipeline.wrapAndCopyInto (AbstractPipeline.java:499)
    at java.util.stream.ReduceOps$ReduceOp.evaluateSequential (ReduceOps.java:921)
    at java.util.stream.AbstractPipeline.evaluate (AbstractPipeline.java:234)
    at java.util.stream.ReferencePipeline.collect (ReferencePipeline.java:682)
    at io.swagger.v3.parser.processors.ExternalRefProcessor.processSchema (ExternalRefProcessor.java:253)
    at io.swagger.v3.parser.processors.ExternalRefProcessor.processSchema (ExternalRefProcessor.java:244)
    at io.swagger.v3.parser.processors.ExternalRefProcessor.processRefSchemaObject (ExternalRefProcessor.java:1009)
    at io.swagger.v3.parser.processors.ExternalRefProcessor.processPathItem (ExternalRefProcessor.java:350)
    at io.swagger.v3.parser.processors.ExternalRefProcessor.processRefToExternalPathItem (ExternalRefProcessor.java:325)
    at io.swagger.v3.parser.processors.PathsProcessor.processReferencePath (PathsProcessor.java:346)
    at io.swagger.v3.parser.processors.PathsProcessor.processPaths (PathsProcessor.java:68)
    at io.swagger.v3.parser.OpenAPIResolver.resolve (OpenAPIResolver.java:72)
    at io.swagger.v3.parser.OpenAPIResolver.resolve (OpenAPIResolver.java:59)
    at io.swagger.v3.parser.OpenAPIV3Parser.resolve (OpenAPIV3Parser.java:240)
    at io.swagger.v3.parser.OpenAPIV3Parser.readContents (OpenAPIV3Parser.java:183)
    at io.swagger.v3.parser.OpenAPIV3Parser.readLocation (OpenAPIV3Parser.java:97)
    at io.swagger.parser.OpenAPIParser.readLocation (OpenAPIParser.java:16)
    at org.openapitools.codegen.config.CodegenConfigurator.toContext (CodegenConfigurator.java:687)
    at org.openapitools.codegen.config.CodegenConfigurator.toClientOptInput (CodegenConfigurator.java:745)
    at org.openapitools.codegen.plugin.CodeGenMojo.execute (CodeGenMojo.java:972)
    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:103)
    at java.lang.reflect.Method.invoke (Method.java:580)
    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)

Is this expected? Can I avoid this in some other way, except creating TypeC, TypeD etc?

[jpfinne]

7.14.0 upgraded the swagger parser. The parser can not parse your specs.
See #21325

Multiple keys mapping to a songle TypeB is probably not supported. Check on https://github.com/swagger-api/swagger-parser

[IgorMaj]

Thank you for your response. I'll check it out.
Follow up issue on their GH here.

[emakar]

@jpfinne This should be supported as per OAI/OpenAPI-Specification#3283 ?