[CODEGEN-CLI] Exception while resolving external $REF

Description

With version 3.0.35 of the swagger-codegen-cli there is an error when resolving external $refs. This error does not occur with version 3.0.34.

11:21:13.876 [Thread-0] WARN  io.swagger.v3.parser.OpenAPIV3Parser - Exception while resolving:
java.lang.RuntimeException: Unable to load RELATIVE ref: foo.bar path: /path/to/openapi
	at io.swagger.v3.parser.util.RefUtils.readExternalRef(RefUtils.java:243)
	at io.swagger.v3.parser.ResolverCache.loadRef(ResolverCache.java:150)
	at io.swagger.v3.parser.processors.ParameterProcessor.processParameters(ParameterProcessor.java:89)
	at io.swagger.v3.parser.processors.OperationProcessor.processOperation(OperationProcessor.java:46)
	at io.swagger.v3.parser.processors.PathsProcessor.processPaths(PathsProcessor.java:88)
	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:226)
	at io.swagger.v3.parser.OpenAPIV3Parser.readContents(OpenAPIV3Parser.java:178)
	at io.swagger.v3.parser.OpenAPIV3Parser.readLocation(OpenAPIV3Parser.java:94)
	at io.swagger.parser.OpenAPIParser.readLocation(OpenAPIParser.java:16)
	at io.swagger.codegen.v3.config.CodegenConfigurator.toClientOptInput(CodegenConfigurator.java:612)
	at io.swagger.codegen.v3.cli.cmd.Generate.run(Generate.java:386)
	at java.base/java.lang.Thread.run(Thread.java:829)
Caused by: java.lang.RuntimeException: Could not find foo.bar on the classpath
	at io.swagger.v3.parser.util.ClasspathHelper.loadFileFromClasspath(ClasspathHelper.java:31)
	at io.swagger.v3.parser.util.RefUtils.readExternalRef(RefUtils.java:237)
	... 13 common frames omitted
11:21:13.892 [Thread-0] WARN  io.swagger.v3.parser.OpenAPIV3Parser - Exception while resolving:
java.lang.RuntimeException: Unable to load RELATIVE ref: foo.bar path: /path/to/openapi
	at io.swagger.v3.parser.util.RefUtils.readExternalRef(RefUtils.java:243)

       ....

Swagger-codegen version

swagger-codegen-cli-3.0.35.jar

Swagger declaration file content or url

      parameters:
        - $ref: 'parameters.yml#/foo.bar'

Command line used for generation

$ java -jar swagger-codegen-cli-3.0.35.jar generate -l openapi-yaml -i $OPENAPI_TMP/temp.yml -o ./$OPENAPI_TMP -DoutputFile=generated-openapi.yml

Start at RefUtils.readExternalRef and ResolverCache.loadRef in the stack trace, then reproduce the issue with the supplied parameters.yml reference and the swagger-codegen-cli 3.0.35 command. Compare the behavior with 3.0.34; done means the relative external $ref resolves without the reported exception during generation.