Don't extract referenced bundles for Maven runtime classpath

Fixes #923

OSGi bundles that are referenced by the m2e.maven.runtime bundle don't
have to be extracted when added to classpath of an about to be launched
Maven build.
This significantly speeds up opening the first time the Launch-Config
dialog for Maven builds or the Maven Installation settings.

Additionally ensure that slf4j from Maven-Central instead of the Orbit
version to prevent errors like the following when launching a
Maven-build with the embedded runtime from the IDE:
class "org.slf4j.MavenSlf4jFriend"'s signer information does not match
signer information of other classes in the same package

The reason is that the slf4j variant from Orbit is jar-signed by
Eclipse, while 'slf4j' and 'maven-slf4j-provider' from Maven-Central is
only PGP-signed (and not jarsigned). But because 'slf4j' and
'maven-slf4j-provider' provide classes for the package org.slf4j they
must provide the same signer information.

m2e-maven-runtime/org.eclipse.m2e.maven.runtime/pom.xml

@@ -169,9 +169,9 @@
 								com.google.inject.*;provider=m2e;mandatory:=provider,\
 								io.takari.*;provider=m2e;mandatory:=provider
 							Import-Package: \
-								org.slf4j;resolution:=optional;version="[1.7.0,3.0.0)",\
-								org.slf4j.spi;resolution:=optional;version="[1.7.0,3.0.0)",\
-								org.slf4j.helpers;resolution:=optional;version="[1.7.0,3.0.0)",\
+								org.slf4j;resolution:=optional;version="[1.7.31,3.0.0)",\
+								org.slf4j.spi;resolution:=optional;version="[1.7.31,3.0.0)",\
+								org.slf4j.helpers;resolution:=optional;version="[1.7.31,3.0.0)",\
 								javax.inject;version="1.0.0",\
 								javax.annotation;version="[1.2.0,2.0.0)",\
 								javax.annotation.sql;version="[1.2.0,2.0.0)",\

org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/Bundles.java

@@ -20,8 +20,8 @@
 import java.util.Arrays;
 import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.NoSuchElementException;
 import java.util.Set;
-import java.util.stream.Collectors;
 
 import org.osgi.framework.Bundle;
 import org.osgi.framework.BundleException;
@@ -38,6 +38,8 @@
  * @since 1.5
  */
 public class Bundles {
+  private Bundles() {
+  }
 
   private static final Logger log = LoggerFactory.getLogger(Bundles.class);
 
@@ -50,7 +52,13 @@ public static List<String> getClasspathEntries(Bundle bundle) {
     cp.addAll(parseBundleClasspath(bundle));
     List<String> entries = new ArrayList<>();
     for(String cpe : cp) {
-      String entry = getClasspathEntryPath(bundle, ".".equals(cpe) ? "/" : cpe);
+      String entry;
+      if(".".equals(cpe)) {
+        entry = FileLocator.getBundleFileLocation(bundle)
+            .orElseThrow(() -> new NoSuchElementException("Unable to locate bundle:" + bundle)).toString();
+      } else {
+        entry = getClasspathEntryPath(bundle, cpe);
+      }
       if(entry != null) {
         log.debug("\tEntry:{}", entry);
         entries.add(entry);
@@ -64,7 +72,7 @@ private static List<String> parseBundleClasspath(Bundle bundle) {
     try {
       ManifestElement[] cpEntries = ManifestElement.parseHeader(Constants.BUNDLE_CLASSPATH, header);
       if(cpEntries != null) {
-        return Arrays.stream(cpEntries).map(ManifestElement::getValue).collect(Collectors.toList());
+        return Arrays.stream(cpEntries).map(ManifestElement::getValue).toList();
       }
     } catch(BundleException ex) {
       log.warn("Could not parse bundle classpath of {}", bundle, ex);
@@ -97,12 +105,12 @@ public static String getClasspathEntryPath(Bundle bundle, String cp) {
   }
 
   @SuppressWarnings("restriction")
-  public static List<String> getDevClassPath(String bundleSymbolicName) {
+  private static List<String> getDevClassPath(String bundleSymbolicName) {
     return Arrays.asList(org.eclipse.core.internal.runtime.DevClassPathHelper.getDevClassPath(bundleSymbolicName));
   }
 
   @SuppressWarnings("restriction")
-  public static boolean inDevelopmentMode() {
+  private static boolean inDevelopmentMode() {
     return org.eclipse.core.internal.runtime.DevClassPathHelper.inDevelopmentMode();
   }
 }