Bug 6672 jar no longer exported after attach source
1206 1. Create a project test. 2. Add a jar (say resources.jar) to the classpath and export the entry 3. Attach source (say resourcessrc.zip) to the jar. Notice, the jar is no longer exported - this information is discarded during the attach source process.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/SourceAttachmentBlock.java
if (varName == null) {
					status.setError(NewWizardMessages.getString("SourceAttachmentBlock.filename.error.notvalid")); 
					return status;
				}
				fFileVariablePath= JavaCore.getClasspathVariable(varName);
				if (fFileVariablePath == null) {
					status.setError(NewWizardMessages.getString("SourceAttachmentBlock.filename.error.varnotexists")); 
					return status;
				}
				resolvedPath= fFileVariablePath.append(filePath.removeFirstSegments(1));
				
				if (resolvedPath.isEmpty()) {
					status.setWarning(NewWizardMessages.getString("SourceAttachmentBlock.filename.warning.varempty")); 
					return status;
				}
				File file= resolvedPath.toFile();
				if (!file.isFile()) {				
					String message= NewWizardMessages.getFormattedString("SourceAttachmentBlock.filename.error.filenotexists", resolvedPath.toOSString()); 
					status.setWarning(message);
					return status;
				}						
				fResolvedFile= file;
				
			} else {
				File file= filePath.toFile();
				IResource res= fRoot.findMember(filePath);
				if (res != null) {
					file= res.getLocation().toFile();
				}
				if (!file.isFile()) {