[BUG] Option template directory ignored in 4.1.0-SNAPSHOT

Created by: MichalFoksa

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Bounty to sponsor the fix (example)

Description

Looks like template directory option (-t | --template-dir ) is ignored in 4.1.0-SNAPSHOT. Template directory always defaults to embeded dir.

Following condition from DefaultCodegen.processOpts() evaluates to false even when -t option is provided, e.g: -t swagger/my-template .

if (additionalProperties.containsKey(CodegenConstants.TEMPLATE_DIR))

I have added a log message right at the end of DefaultCodegen.processOpts() method: LOGGER.info("Template directory [templateDir={}]", this.templateDir());

Result message: [main] INFO o.o.codegen.DefaultCodegen - [Template directory [templateDir=openapi-yaml]

BTW: Same issue is with Spring generator.

openapi-generator version

4.1.0-SNAPSHOT as of 14/July/2019.

Steps to reproduce

java -jar "./modules/openapi-generator-cli/target/openapi-generator-cli.jar" generate -i swagger/openapi.yml -g openapi-yaml -t swagger/my-template --additional-properties outputFile=swagger/swagger.yml

Suggest a fix

It looks like there is a quite difference in code gen configuration (e.g.: CodegenConfigurator.java) between 4.0.x and 4.1.0.

I do not know what is a direction in 4.1.x.