Updates.

Author: parubok

.idea/vcs.xml

@@ -1,3 +1,4 @@
+- node factory
 - builder (filter, comparator, etc)
 - concurrency
 - immutable nodes

TODO.md

@@ -3,6 +3,7 @@
 import javax.swing.tree.DefaultMutableTreeNode;
 import java.nio.file.FileSystem;
 import java.nio.file.Path;
+import java.util.Objects;
 
 public class DirectoryNode extends DefaultMutableTreeNode {
 
@@ -24,15 +25,15 @@ public DirectoryNode() {
 
     public DirectoryNode(FileSystem fileSystem) {
         super();
-        this.fileSystem = fileSystem;
+        this.fileSystem = Objects.requireNonNull(fileSystem);
         this.directory = null;
         this.str = "Computer"; // getFileSystem().toString();
     }
 
     public DirectoryNode(Path directory) {
         super();
         this.fileSystem = null;
-        this.directory = directory;
+        this.directory = Objects.requireNonNull(directory);
         this.str = getName(getDirectory());
     }