Add support for building MR jars

This changes enable BND user to set

Multi-Release: true

in a BND file and then creates a bundle that conforms to the OSGi
Multi-release JAR specification

Signed-off-by: Christoph Läubrich <laeubi@laeubi-soft.de>

biz.aQute.bndlib.tests/test/aQute/bnd/osgi/AnalyzerTest.java

@@ -1,7 +1,14 @@
 package aQute.bnd.osgi;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.Optional;
+import java.util.jar.Manifest;
+
 import org.junit.jupiter.api.Test;
 
+import aQute.lib.io.IO;
+
 public class AnalyzerTest {
 
 	@Test
@@ -13,4 +20,36 @@ public void testdoNameSection() throws Exception {
 		}
 	}
 
+	@Test
+	public void multiRelease() throws Exception {
+		try (Analyzer a = new Analyzer(new Jar("test"))) {
+			a.setProperty("Multi-Release", "true");
+			assertThat(a.check()).isTrue();
+			Jar jar = a.getJar();
+			String fooPath = "test/Foo.class";
+			String barPath = "test/Bar.class";
+			jar.putResource(fooPath,
+					new FileResource(IO.getFile("testresources/mr/java8/Foo.class")));
+			jar.putResource(barPath,
+				new FileResource(IO.getFile("testresources/mr/java8/Bar.class")));
+			jar.putVersionedResource(fooPath, 9, new FileResource(IO.getFile("testresources/mr/java9/Foo.class")));
+			jar.putVersionedResource(barPath, 17, new FileResource(IO.getFile("testresources/mr/java17/Bar.class")));
+			jar.setManifest(a.calcManifest());
+			Manifest mainMf = jar.getManifest();
+			Optional<Manifest> java9Mf = jar.getManifest(9);
+			Optional<Manifest> java17Mf = jar.getManifest(17);
+			assertThat(mainMf.getMainAttributes()
+				.getValue(Constants.REQUIRE_CAPABILITY)).isNotNull()
+					.contains("(&(osgi.ee=JavaSE)(version=1.8))");
+			assertThat(java9Mf.get()
+				.getMainAttributes()
+				.getValue(Constants.REQUIRE_CAPABILITY)).isNotNull()
+					.contains("(&(osgi.ee=JavaSE)(version=9))");
+			assertThat(java17Mf.get()
+				.getMainAttributes()
+				.getValue(Constants.REQUIRE_CAPABILITY)).isNotNull()
+					.contains("(&(osgi.ee=JavaSE)(version=17))");
+		}
+	}
+
 }