Make PDE projects adaptable to an OSGi Resource

Currently one needs to use some special PDE API to learn about the OSGi
nature of a project. This is not only cumbersome but also ties the
consumer to a specific tooling.

With this change now any eclipse project can be adapted to an OSGi
Resource making the caller completely tooling independent. That way it
is for example possible to select a PDE project and have it displayed in
the OSGi Resolution view.

Author: laeubi

ui/org.eclipse.pde.bnd.ui/README.MD

@@ -18,7 +18,7 @@ One problem for such a reusable component is that it usually needs to get holds
 To mitigate we use the [Eclipse Adapter Pattern](https://www.eclipse.org/articles/Article-Adapters/) as it is widely used in Eclipse, flexible and allows
 the use of [OSGi services / Dependency Injection](https://eclipse.dev/eclipse/news/4.18/platform_isv.php#dialog-adapterfactory-as-service) already.
 
-### The IProject adapter
+### The `IProject` adapter
 
 Components need to learn the project and workspace of a bndlib backed project, for this the very first step for an integration is to provide an adapter that can
 transform an (Eclipse) `IProject` into a (bndlib) `Project` (from were the Workspace then can be derived), an example might look like this:
@@ -46,6 +46,18 @@ public class MyBndPluginAdapter implements IAdapterFactory {
 }
 ```
 
+## The `Resource` Adapter
+
+Some components might want to learn about an (OSGi) `Resource` (e.g. a Bundle) for a particular object. 
+To support such use-case one should provide an Adapter from tooling specific objects to (OSGi) `Resource`.
+
+For example the previous Adapter might be enhanced to support an adaption from an (Eclipse) `IProject` to an
+(OSGi) `Resource` if it represents a bundle and the tolling knows how to transform the specific project metadata into an universal
+`Resource` representation. That way it is possible to select the project and show its requirements and
+capabilities in the OSGi Resolution View without specific knowledge on how this process works.
+
+### Further Information
+
 Some relevant 'glue' classes for Bnd <-> PDE interaction, to have a look at:
 
 - `org.eclipse.pde.bnd.ui.Central`
@@ -63,6 +75,7 @@ it currently offers these components:
 
 - [bnd templates](https://eclipse.dev/eclipse/news/4.31/pde.php#bndtemplates)
 - [osgi repositories view](https://eclipse.dev/eclipse/news/4.32/pde.php#osgirepositories)
+- [OSGi Resolution View](https://eclipse.dev/eclipse/markdown/?f=news/4.36/pde.md#new-osgi-resolution-view)
 - Formating of bnd files, quick fixes, completion proposals
 - ... more to come ...
 

ui/org.eclipse.pde.core/src/org/eclipse/pde/internal/core/bnd/PdeBndAdapter.java

@@ -13,19 +13,28 @@
  *******************************************************************************/
 package org.eclipse.pde.internal.core.bnd;
 
+import java.io.InputStream;
+import java.util.jar.Manifest;
+
 import org.bndtools.versioncontrol.ignores.manager.api.VersionControlIgnoresManager;
+import org.eclipse.core.resources.IFile;
 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.runtime.AdapterTypes;
 import org.eclipse.core.runtime.IAdapterFactory;
+import org.eclipse.pde.internal.core.natures.PluginProject;
+import org.eclipse.pde.internal.core.project.PDEProject;
+import org.osgi.resource.Resource;
 import org.osgi.service.component.annotations.Component;
 import org.osgi.service.component.annotations.Reference;
 import org.osgi.service.component.annotations.ReferenceCardinality;
 import org.osgi.service.component.annotations.ReferencePolicy;
 
 import aQute.bnd.build.Project;
+import aQute.bnd.osgi.resource.ResourceBuilder;
 
 @Component(service = IAdapterFactory.class)
-@AdapterTypes(adaptableClass = IProject.class, adapterNames = { Project.class, VersionControlIgnoresManager.class })
+@AdapterTypes(adaptableClass = IProject.class, adapterNames = { Project.class, VersionControlIgnoresManager.class,
+		Resource.class })
 public class PdeBndAdapter implements IAdapterFactory {
 
 	@Reference(cardinality = ReferenceCardinality.OPTIONAL, policy = ReferencePolicy.DYNAMIC)
@@ -46,6 +55,24 @@ public <T> T getAdapter(Object adaptableObject, Class<T> adapterType) {
 		if (adapterType == VersionControlIgnoresManager.class) {
 			return adapterType.cast(versionControlIgnoresManager);
 		}
+		if (adapterType == Resource.class) {
+			if (adaptableObject instanceof IProject project) {
+				if (PluginProject.isPluginProject(project)) {
+					IFile manifestFile = PDEProject.getManifest(project);
+					if (manifestFile != null && manifestFile.exists()) {
+						Manifest manifest;
+						try (InputStream stream = manifestFile.getContents()) {
+							manifest = new Manifest(stream);
+						} catch (Exception e) {
+							return null;
+						}
+						ResourceBuilder builder = new ResourceBuilder();
+						builder.addManifest(manifest);
+						return adapterType.cast(builder.build());
+					}
+				}
+			}
+		}
 		return null;
 	}