Add Apache v2 license to auto-generated files

[wing328]

We will update the auto-generated files for all languages (both API clients and server stubs).
#2960 for C# API client is a good reference.

API clients

• Android
• C++
• C# ([C#] add apache v2 license to C# API client #2960)
• Clojure
• Dart
• Flash
• Go
• Javascript
• Java
• ObjC
• Perl
• PHP ([PHP] Add apache v2 license to PHP client #2971)
• Python ([Python] Include license in generated client #2972)
• Ruby ([Ruby] update Ruby API client to use apache v2 license #2946 [Ruby] add apache v2 license to remaining ruby files (test, spec, etc) #2951 [Ruby] add licence template for ruby api client #2953)
• Swift
• Scala
• TypeScript

Server stubs

• C# ASP.NET5
• Haskell Servant
• Java Spring Boot
• JAX-RS RestEas
• JAX-RS CXF
• PHP Lumen
• PHP Slim
• Ruby on Rails 5
• Scalatra (Add Apache v2 license to auto-generated scalatra files. #3122)

[ePaul]

Is this needed for some legal reason? Also, is this legally sound?

One could say that the generated code is derived from both the template files (which certainly have the same license as the rest of this project) and the API definition – the latter one is provided by the user, and could have conflicting licensing requirements (e.g. a copyleft license as GPL). In that case I guess the generated code would need to be GPL, too (or the user would not be allowed to use the generator).

[wing328]

@ePaul thanks for your questions and please refer to the following discussion for more information.

https://groups.google.com/forum/#!searchin/swagger-swaggersocket/license/swagger-swaggersocket/6JcsR4mWpYk/pd3__T0mHwAJ

https://twitter.com/TimHaines/status/729717172889489408

Disclaimer: I'm no expert in software licensing

[ePaul]

@wing328 Thanks. Just for the future, it would be nice if (in cases there has been some discussion) this discussion is linked right when the issue is opened, so people know why stuff is done.

[wing328]

Yup, definitely valid point. I've been trying my best to keep the community informed but sometimes I did miss it. Feel free to ask whenever you've questions for us.

[xtoddx]

tl;dr: You should license the template files Apache 2, but not assume it applies it to the resulting generated code.

The reasoning in the linked discussions is not sound. Swift is licensed Apache 2, but not every application built using the swift compiler is infected with the same license. Only the most viral licenses work this way, and Apache is not one of them. In the same way, since the templates are processed and the generated code represents a new product, the license does not persist. I'm not a lawyer, but this seems to be the intent of the license and of the swagger team.

If you make an exception (making Apache viral across swagger-codegen use) and put the license on the generated code, it isn't as simple as "do what you want". You must state changes, grant use of patents, and otherwise comply with the terms of the Apache License.... otherwise what you have is just some comments in a header and not really a license. The output code is also possibly further restricted in use by the input swagger definition, which may be incompatible with Apache 2 or not be relicensable. Specifically, Mozilla and GPL* are not relicensable (but I don't know if people actually license their swagger defs under those licenses, though I imagine AGPL is likely to come up).

Putting the Apache 2 license in the resulting files:

• is against the stated "do what you want" position of some of the swagger team
• makes the Apache 2 license more viral than it really is
• ignores other licensing constraints on the generated code
• makes adoption less likely in risk-averse institutions
• rolls back community precedent for generated code/objects w/r/t licensing (using GCC stops the GPL3 infection in most circumstances)

At the end of the day, putting the license in the generated code violates user expectations, is probably not the intent of the license or the developers, and makes adoption more risky/complicated.