Add Provide-Capability OSGi header to engine bundles

Fixes #2100. Closes #2544.

Author: kriegfrj

junit-jupiter-engine/junit-jupiter-engine.gradle.kts

@@ -1,3 +1,4 @@
+import aQute.bnd.gradle.BundleTaskConvention
 import org.gradle.api.tasks.PathSensitivity.RELATIVE
 
 plugins {
@@ -28,3 +29,16 @@ tasks {
 		inputs.dir("src/test/resources").withPathSensitivity(RELATIVE)
 	}
 }
+
+tasks {
+	jar {
+		withConvention(BundleTaskConvention::class) {
+			bnd("""
+				Provide-Capability:\
+					org.junit.platform.engine;\
+						org.junit.platform.engine='junit-jupiter';\
+						version:Version="${'$'}{version_cleanup;${project.version}}"
+			""")
+		}
+	}
+}

junit-vintage-engine/junit-vintage-engine.gradle.kts

@@ -1,4 +1,4 @@
-import aQute.bnd.gradle.BundleTaskConvention;
+import aQute.bnd.gradle.BundleTaskConvention
 
 plugins {
 	`java-library-conventions`
@@ -47,6 +47,11 @@ tasks {
 					org.junit.runner.*;version="[${junit4Min},5)",\
 					org.junit.runners.model;version="[${junit4Min},5)",\
 					*
+
+				Provide-Capability:\
+					org.junit.platform.engine;\
+						org.junit.platform.engine='junit-vintage';\
+						version:Version="${'$'}{version_cleanup;${project.version}}"
 			""")
 		}
 	}