fix ClassCastException in CapReqComparator

- reason was that the namespace 'osgi.ee' can contain List<Version>
- so we now handle cases of single Version vs. List<Version>
- for lists we take the highest version for comparison

Author: chrisrueger

ui/org.eclipse.pde.bnd.ui/src/org/eclipse/pde/bnd/ui/model/resolution/CapReqComparator.java

@@ -15,6 +15,7 @@
 *******************************************************************************/
 package org.eclipse.pde.bnd.ui.model.resolution;
 
+import java.util.Collection;
 import java.util.Comparator;
 
 import org.eclipse.pde.bnd.ui.model.resource.R5LabelFormatter;
@@ -85,16 +86,29 @@ private int compareCapToCap(Capability c1, Capability c2) {
 		String versionAttribName = R5LabelFormatter.getVersionAttributeName(ns1);
 		if (versionAttribName == null)
 			return 0;
-		Version v1 = (Version) c1.getAttributes()
-			.get(versionAttribName);
-		if (v1 == null)
-			v1 = Version.emptyVersion;
-		Version v2 = (Version) c2.getAttributes()
-			.get(versionAttribName);
-		if (v2 == null)
-			v2 = Version.emptyVersion;
+		
+		Version v1 = highestVersion(c1.getAttributes().get(versionAttribName));
+	    Version v2 = highestVersion(c2.getAttributes().get(versionAttribName));
+	    
 		return v1.compareTo(v2);
 	}
+	
+	private static Version highestVersion(Object attr) {
+	    if (attr instanceof Version v) {
+	        return v;
+	    }
+	    if (attr instanceof Collection<?> col) {
+	    	// e.g. namespace 'osgi.ee' can contain List<Version>
+	    	// see https://osgi.github.io/osgi/core/framework.namespaces.html#framework.namespaces-ee.namespace
+	    	// so we compare the highest versions
+	        return col.stream()
+	                  .filter(Version.class::isInstance)
+	                  .map(Version.class::cast)
+	                  .max(Version::compareTo)
+	                  .orElse(Version.emptyVersion);
+	    }
+	    return Version.emptyVersion;  // null or wrong type
+	}
 
 	private int compareReqToReq(Requirement r1, Requirement r2) {
 		return ResourceUtils.REQUIREMENT_COMPARATOR.compare(r1, r2);