Fixed ignoring npm name and version properties

[szymonbultrowicz]

It looks like current version of GenerateTask.java has a wrong condition when setting npmName and npmVersion properties. I assume it should work like that (if generateNpmPackageJson is set to true):

1. npmName/npmVersion not set -> use default value
2. npmName/npmVersion set -> use given value

However, currently it works like that:

1. npmName/npmVersion not set -> error is being thrown with message that those properties are required
2. npmName/npmVersion set -> uses default values (ignores the given ones)

This PR fixes that issue.

[vojtechhabarta]

You are right, it's wrong.

You are also right that it should generate default value when

1. the value is not filled and
2. generateNpmPackageJson is true.

The second part is missing in your PR.

I think that what's needed is just to flip null tests. Then if generateNpmPackageJson is false but value is null then it stays null.

See this in Maven plugin here: https://github.com/vojtechhabarta/typescript-generator/blob/master/typescript-generator-maven-plugin/src/main/java/cz/habarta/typescript/generator/maven/GenerateMojo.java#L578-L579

What do you think?

[szymonbultrowicz]

Actually, I think there is no need to check if the flag is true. Without it, the condition is simpler and those values are going to be ignored, anyway. Although, if you think it's better to check it, I'll do it, no problem.

[vojtechhabarta]

Currently if generateNpmPackageJson is false the values are NOT silently ignored but Settings.validate() complains that they can only be used when generateNpmPackageJson is true. I know it's rather pedantic 😄 but I wanted to give users detailed feedback when they're configuring typescript-genereator.

See https://github.com/vojtechhabarta/typescript-generator/blob/master/typescript-generator-core/src/main/java/cz/habarta/typescript/generator/Settings.java#L270

[szymonbultrowicz]

Got it. Fixed.

[vojtechhabarta]

Merged. Thank you very much.