[BUG] Maven-plugin - Build fails if inputSpecs are a file from a remote URL

[RockyMM]

Description

If an URL is used as the inputSpecs, the build fails at the very end (all files are generated) with:

INFO] writing file D:\Projects\mdh-gen\mdh-modelgen-test\target\generated-sources\mdh\.openapi-generator-ignore
[INFO] writing file D:\Projects\mdh-gen\mdh-modelgen-test\target\generated-sources\mdh\.openapi-generator\VERSION
[ERROR] D:\Projects\mdh-gen\mdh-modelgen-test\https:\test.com\swagger\spec\mdh.yml [0:0]: unexpected error in Open-API generation
D:\Projects\mdh-gen\mdh-modelgen-test\https:\test.com\swagger\spec\mdh.yml [0:0]: unexpected error in Open-API generation


java.lang.RuntimeException: Could not find https:/test.com/swagger/spec/mdh.yml on the classpath
    at io.swagger.v3.parser.util.ClasspathHelper.loadFileFromClasspath (ClasspathHelper.java:31)
    at org.openapitools.codegen.plugin.CodeGenMojo.execute (CodeGenMojo.java:706)
    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)

openapi-generator version

Maven plugin version

            <groupId>org.openapitools</groupId>
            <artifactId>openapi-generator-maven-plugin</artifactId>
            <version>4.1.1</version>

OpenAPI declaration file content or url

https://github.com/RockyMM/openapi-modelgen-test/blob/master/src/main/openapi/mdh.yml

Command line used for generation

mvn clean generate-sources

Steps to reproduce

In the test project above set inputSpec to be an URL of a remote file.
Run mvn clean generate-sources on the test project.

Suggest a fix

In the class:

https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator-maven-plugin/src/main/java/org/openapitools/codegen/plugin/CodeGenMojo.java

Seems that inputSpecFile.exists() is not doing it's job properly.

[wing328]

Can you try the latest master, which should have the issue addressed?

Happy to reopen the issue if it's not the case

[RockyMM]

I will have a busy week, so I cannot test it until next week. If the release is coming soon I could test with 4.1.2; that would be much simpler for me :)

[RockyMM]

Likely duplicate of #3440