[cli] Generator logs to STDOUT when debug options are set

Created by: devplayer0

Description

Since #207, log messages are written to STDOUT and STDERR respectively based on the level of the message, which makes sense.

However, when debugging the models / operations passed to the templates, it would be nice to be able to pipe the JSON directly into a file / program which could parse it directly. Currently the piped output will include any of the messages written to STDOUT (which is everything except for errors), which means that it is unparsable.

openapi-generator version

Latest from master

OpenAPI declaration file content or url

N/A

Command line used for generation

java -DdebugModels -jar openapi-generator/modules/openapi-generator-cli/target/openapi-generator-cli.jar generate -g java -i cellar.json -o /tmp/cellar > generate.json

Steps to reproduce

Pipe the output of any generate command with a debug flag set (such as debugModels or debugOperations)

Related issues/PRs

This is in direct response to #207.

Suggest a fix/enhancement

See PR #474