[JAVA] Invalid java code is generated

Description

I'm trying to generate the API based on the fido2-server.yaml. The generated java code is invalid.
Due to the environment restriction I have to use swagger v2.0. Any idea's how to solve this?

Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.0:compile (default-compile) on project fido2.swagger: Compilation failure: Compilation failure:
/c:/dev/prj/hanndecl/fido2-swagger/target/generated-sources/openapi-server/src/main/java/io/swagger/api/AssertionApi.java:[74,204] <identifier> expected
/c:/dev/prj/hanndecl/fido2-swagger/target/generated-sources/openapi-server/src/main/java/io/swagger/api/AttestationApi.java:[74,206] <identifier> expected

Swagger-codegen version

<groupId>io.swagger</groupId>
<artifactId>swagger-codegen-maven-plugin</artifactId>
<version>2.3.1</version>

Swagger declaration file content or url

Maven project: https://github.com/hanndecl/fido2-swagger

Command line used for generation

see https://github.com/hanndecl/fido2-swagger/pom.xml

Steps to reproduce

{code}
maven clean install
{code}

Start with the Maven configuration in the linked fido2-swagger project's pom.xml and run the reported maven clean install reproduction. Inspect the generated AssertionApi.java and AttestationApi.java files at the reported compiler locations. Done means the generated Java sources compile successfully under swagger-codegen 2.3.1.