[Build] Generate OSGi metadata for JSVG

[HannesWell]

This change has the goal to extend the jar's META-INF/MANIFEST.MF generated during the build to contiain OSGi metadata so that JSVG can be used as bundle in OSGi runtimes out of the box.
This is needed for eclipse-platform/eclipse.platform.swt#1638

To generate OSGi metadata the bnd-tools library is used respectivly it's gradle plugin.
While I know how to configure bnd-tools, for JSVG it should actually be quite simple since there are no dependencies, I have almost zero knowledge about Gradle and how to integrate the bnd-gradle plugin into JSVG's build and failed in my attempts to make it work.
I tried to follow the guide provided at:
https://github.com/bndtools/bnd/tree/master/gradle-plugins#gradle-plugin-for-non-bnd-workspace-builds ff

@weisJ could you please advice me what I need to do in order to make the bnd-gradle plugin work?
Then i can work out a suitable bnd-configuration to generated proper OSGi metadata. Therefore this is currently a work-in-progress draft to get the work started.
Thanks in advance!

[HannesWell]

@Michael5601 FYI.

@weisJ if it would helpful, I can offer to have video-call, maybe together with @Michael5601, to make this work.
I had a private mail coversiation with Michael about this and he said, you are in contact. If you are interested, maybe Michael could start a private mail conversion for an appointment?

[weisJ]

I have just pushed a commit to your branch which makes the plugin work. You should now be able to configure the bundle properties.

[Michael5601]

@Michael5601 FYI.

@weisJ if it would helpful, I can offer to have video-call, maybe together with @Michael5601, to make this work. I had a private mail coversiation with Michael about this and he said, you are in contact. If you are interested, maybe Michael could start a private mail conversion for an appointment?

Thank you for the draft and the work you put into this already @HannesWell. Should I still create the appointment or is the problem fixed by the commit of @weisJ?

[HannesWell]

I have just pushed a commit to your branch which makes the plugin work. You should now be able to configure the bundle properties.

Thanks a lot. I was now to configure the bundle task, but only through the manifest-attributes as described in the last section of
https://github.com/bndtools/bnd/tree/master/gradle-plugins#instructing-bnd-on-how-to-build-your-bundle

I also tried to use, what I think is the regular way, through a bnd element in the bundle task, but failed miserably. Sorry for that, but I have really zero knowledge about Gradle. I tried hard to find something through internet search, etc. but failed. I you have better advice, I would be very glad.

[HannesWell]

When I added the following, the configuration was just ignored and the generated MANIFEST.MF in weisJ-jsvg\jsvg\build\libs\jsvg-1.6.2-SNAPSHOT.jar did had the content that should result from the specified instructions.

Suggested change

	bundle {
	}
	bundle {
	bnd("""
	Bundle-SymbolicName: com.github.weisj.jsvg
	-exportcontents: !*.impl.*,*
	-removeheaders: Private-Package,Tool
	""")
	}

[HannesWell]

Adding the bnd instruction to a separate bundle task (?) here

Suggested change

	}
	}
	bundle {
	bnd("""
	Bundle-SymbolicName: com.github.weisj.jsvg
	-exportcontents: !*.impl.*,*
	-removeheaders: Private-Package,Tool
	""")
	}

lead to a build failure with:

Could not determine the dependencies of task ':annotations:assemble'.
> Could not create task ':annotations:sourcesJar'.
   > Extension with name 'bundle' does not exist. Currently registered extension names: [ext]

[HannesWell]

The current state is probably not beautiful, but seems to work, although I think some parts can be cleaned up?
If possible, it might still be cleaner to make the bnd element within a bundle task work?

@Michael5601 FYI.
@weisJ if it would helpful, I can offer to have video-call, maybe together with @Michael5601, to make this work. I had a private mail coversiation with Michael about this and he said, you are in contact. If you are interested, maybe Michael could start a private mail conversion for an appointment?

Thank you for the draft and the work you put into this already @HannesWell. Should I still create the appointment or is the problem fixed by the commit of @weisJ?

From my point of view this is not necessary, I hope we can sort out the remaining issues here. But if any one of you is still interested I'm open for it. :)