Handle intentional (spot) bug

todolist/fxutil/src/main/java/fxutil/SuppressFBWarnings.java

+package fxutil;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * Annontation to suppress spotbugs warnings.
+ * Must have this specific name to be considered by spotbugs.
+ */
+@Retention(RetentionPolicy.CLASS)
+public @interface SuppressFBWarnings {
+  /**
+   * The set of FindBugs warnings that are to be suppressed in
+   * annotated element. The value can be a bug category, kind or pattern.
+   */
+  String[] value() default {};
+
+  /**
+   * Optional documentation of the reason why the warning is suppressed.
+   */
+  String justification() default "";
+}

todolist/fxutil/src/main/java/fxutil/doc/FileMenuController.java

 package fxutil.doc;
 
+import fxutil.SuppressFBWarnings;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
@@ -35,6 +36,9 @@ public class FileMenuController {
    *
    * @param documentStorage the document storage
    */
+  @SuppressFBWarnings(
+      value = "EI_EXPOSE_REP2", 
+      justification = "We intentioanlly don't deep copy documentStorage")
   public void setDocumentStorage(final DocumentStorage<File> documentStorage) {
     this.documentStorage = documentStorage;
     if (importMenu != null) {