[BUG][CLI][GENERATOR] NullPointer when not setting outputDir (updated) (#3752)

* Fixes NPE when no outputDir is set

* Fix behaviors of default values for values not provided by user

* Easier handling of default behavior in settings.

* Fixes for dynamic config deserialization (specifically, ruby client sample fix)

* Tests for WorkflowSettings (defaults, modified defaults, nulls)

* Test modification of WorkflowSettings defaults for both class constructor and builder

modules/openapi-generator/src/main/java/org/openapitools/codegen/config/CodegenConfigurator.java

@@ -91,6 +91,7 @@ public class CodegenConfigurator {
                 DynamicSettings settings = mapper.readValue(new File(configFile), DynamicSettings.class);
                 CodegenConfigurator configurator = new CodegenConfigurator();
                 configurator.generatorSettingsBuilder = GeneratorSettings.newBuilder(settings.getGeneratorSettings());
+                configurator.workflowSettingsBuilder = WorkflowSettings.newBuilder(settings.getWorkflowSettings());
                 return configurator;
             } catch (IOException ex) {
                 LOGGER.error("Unable to deserialize config file: " + configFile, ex);