Can we use an SPDX Expression in the Bundle-License header?

[waynebeaton]

For the contents of the Bundle-License header, the specification states (in part) that...

This identifier should be one of the identifiers defined by [25] Software Package Data Exchange (SPDX) License List.

In cases where content is multiply licensed, it states that you should separate the individual licenses with a comma.

While it is probably reasonable to assume a dual-licensing scenario in which an adopter can choose the license that they prefer to consume the content under (or in SPDX), this is not necessarily the case. There may be cases where the adopter has to accept the terms of multiple licenses (and in SPDX).

The use of the word should when describing the license-identifier and that the header is described as purely informational gives us some flexibility.

So here's the question... would it be considered within the spirit/intention of the requirements of the Bundle-License header to specify an SPDX expression? And, since this information is described as purely informational can we safely assume that providing an SPDX expression shouldn't break anything?

e.g.,

Bundle-License: EPL-2.0 or GPL-2.0-only with Classpath-Exception-2.0

[tjwatson]

https://docs.osgi.org/specification/osgi.core/8.0.0/framework.module.html#framework.module-bundle-license also states:

The Bundle-License header provides an optional machine readable form of license information. The purpose of this header is to automate some of the license processing required by many organizations like for example license acceptance before a bundle is used. The header is structured to provide the use of unique license naming to merge acceptance requests, as well as links to human readable information about the included licenses. This header is purely informational for management agents and must not be processed by the OSGi Framework.

While this header is not parsed by the OSGI Framework itself it still is expected to be machine readable and can be parsed by things like management agents (e.g. p2). The syntax defined by the specification does would not allow you to insert and, or keywords like that without some enhancements to the syntax.

[tjwatson]

My reference to p2 was only as an example. I don't think p2 actually reads this header at all.

[timothyjward]

We should update this in the core specification for the next release