[RETROFIT2] Problem: com.github.jknack.handlebars.HandlebarsException

Description

Cannot generate gradle module because of runtime exception with retrofit2.
Using RxJava2 also.

Swagger-codegen version

3.0.1

Swagger declaration file content or url

I cannot post API, cause it is internal in the company.

Exception in thread "Thread-0" java.lang.RuntimeException: Could not generate api file for 'Department'
	at io.swagger.codegen.v3.DefaultGenerator.generateApis(DefaultGenerator.java:523)
	at io.swagger.codegen.v3.DefaultGenerator.generate(DefaultGenerator.java:722)
	at io.swagger.codegen.v3.cli.cmd.Generate.run(Generate.java:342)
	at java.base/java.lang.Thread.run(Thread.java:844)
Caused by: com.github.jknack.handlebars.HandlebarsException: /handlebars/Java/libraries/retrofit2/api_test.mustache:31:8: found: 'ƒ'
    {{#@ƒirst}}
        ^

	at com.github.jknack.handlebars.internal.HbsErrorReporter.syntaxError(HbsErrorReporter.java:93)
	at org.antlr.v4.runtime.ProxyErrorListener.syntaxError(ProxyErrorListener.java:65)
	at com.github.jknack.handlebars.internal.HbsParserFactory$2.notifyListeners(HbsParserFactory.java:148)

Command line used for generation

swagger-codegen generate -i openapi.json -l java -c config.json -o /Users/mmdo/apis/test/

Steps to reproduce

Just run the script

Related issues/PRs

Suggest a fix/enhancement

Probably an injection into the script occured