Make minor tweaks, based on code review

Author: Eswcvlad

src/main/java/com/itextpdf/rups/controller/IRupsController.java

@@ -63,7 +63,7 @@ public interface IRupsController {
     /**
      * Returns the currently loaded File.
      *
-     * @return PdfFile
+     * @return IPdfFile
      */
     IPdfFile getCurrentFile();
 

src/main/java/com/itextpdf/rups/controller/RupsController.java

@@ -55,6 +55,7 @@ This file is part of the iText (R) project.
 import java.awt.Component;
 import java.awt.Dimension;
 import java.io.File;
+import java.util.Objects;
 import java.util.Observable;
 import java.util.Observer;
 import javax.swing.event.ChangeEvent;
@@ -136,8 +137,9 @@ public final void closeCurrentFile() {
     @Override
     public void reopenAsOwner() {
         final IPdfFile file = this.getCurrentFile();
-        // Should not happen (i.e. UI should not allow it), will silently ignore
+        // Should not happen (i.e. UI should not allow it), will just noop
         if (file == null) {
+            LoggerHelper.warn(Language.ERROR_NO_OPEN_DOCUMENT.getString(), getClass());
             return;
         }
 
@@ -172,7 +174,7 @@ public final void openNewFile(File file) {
     }
 
     private void openNewFileAsOwner(File file) {
-        assert file != null;
+        Objects.requireNonNull(file);
 
         // We don't check here for duplicate files, as we don't want to close
         // the already opened file, if we fail here

src/main/java/com/itextpdf/rups/event/DisplayedTabChanged.java

@@ -44,6 +44,10 @@ This file is part of the iText (R) project.
 
 import com.itextpdf.rups.model.IPdfFile;
 
+/**
+ * Event to signify, that on the main window a different PDF file tab was
+ * selected and displayed (i.e. the displayed file was changed).
+ */
 public class DisplayedTabChanged extends RupsEvent {
     private final IPdfFile displayedFile;
 

src/main/java/com/itextpdf/rups/event/ReopenCurrentFileAsOwnerEvent.java

@@ -43,6 +43,10 @@ This file is part of the iText (R) project.
 package com.itextpdf.rups.event;
 
 
+/**
+ * Event to signify, that a user requested to reopen the currently displayed
+ * protected PDF file as an owner.
+ */
 public class ReopenCurrentFileAsOwnerEvent extends RupsEvent {
     public ReopenCurrentFileAsOwnerEvent() {
         // Nothing to initialize

src/main/java/com/itextpdf/rups/event/RupsEvent.java

@@ -65,8 +65,8 @@ public abstract class RupsEvent {
     public static final byte NEW_INDIRECT_OBJECT_EVENT = 15;
     public static final byte POST_NEW_INDIRECT_OBJECT_EVENT = 16;
     public static final byte ALL_FILES_CLOSED = 17;
-    public static final byte DISPLAYED_TAB_CHANGED = 19;
-    public static final byte REOPEN_CURRENT_FILE_AS_OWNER = 20;
+    public static final byte DISPLAYED_TAB_CHANGED = 18;
+    public static final byte REOPEN_CURRENT_FILE_AS_OWNER = 19;
 
     public abstract int getType();
 

src/main/java/com/itextpdf/rups/model/DialogPasswordProvider.java

@@ -53,19 +53,34 @@ This file is part of the iText (R) project.
 import javax.swing.JOptionPane;
 import javax.swing.JPasswordField;
 
+/**
+ * Password provider implementation, which queries the user for a password via
+ * an interactive GUI dialog.
+ */
 public class DialogPasswordProvider implements IPasswordProvider {
     public static final int MAX_PASSWORD_BYTE_LENGTH = 127;
 
+    /**
+     * Title for the interactive GUI dialog.
+     */
     private final String title;
 
     public DialogPasswordProvider(String title) {
         this.title = title;
     }
 
+    /**
+     * Creates a dialog password provider, which will ask the user for a
+     * password without specifying a concrete type (user or owner).
+     */
     public static DialogPasswordProvider anyPassword() {
         return new DialogPasswordProvider(Language.ENTER_ANY_PASSWORD.getString());
     }
 
+    /**
+     * Creates a dialog password provider, which will ask the user
+     * specifically for an owner password.
+     */
     public static DialogPasswordProvider ownerPassword() {
         return new DialogPasswordProvider(Language.ENTER_OWNER_PASSWORD.getString());
     }

src/main/java/com/itextpdf/rups/view/Language.java

@@ -116,6 +116,7 @@ public enum Language {
     ERROR_LOADING_XFA,
     ERROR_LOOK_AND_FEEL,
     ERROR_MISSING_PASSWORD,
+    ERROR_NO_OPEN_DOCUMENT,
     ERROR_NO_OPEN_DOCUMENT_COMPARE,
     ERROR_ONLY_OPEN_ONE_FILE,
     ERROR_OPENING_FILE,

src/main/resources/bundles/rups-lang.properties

@@ -66,6 +66,7 @@ ERROR_LOADING_IMAGE=Image can't be loaded.
 ERROR_LOADING_XFA=Can't load XFA.
 ERROR_LOOK_AND_FEEL=Error setting the look and feel.
 ERROR_MISSING_PASSWORD=The required password for this document was not provided.
+ERROR_NO_OPEN_DOCUMENT=There is no open document.
 ERROR_NO_OPEN_DOCUMENT_COMPARE=There is no open document. Nothing to compare with.
 ERROR_ONLY_OPEN_ONE_FILE=You can only open one file!
 ERROR_OPENING_FILE=Error opening file: %s

src/main/resources/bundles/rups-lang_en_US.properties

@@ -57,6 +57,7 @@ ERROR_KEY_IS_NOT_NAME=Key value isn't value Name object.
 ERROR_LOADING_IMAGE=Image can't be loaded.
 ERROR_LOADING_XFA=Can't load XFA.
 ERROR_MISSING_PASSWORD=The required password for this document was not provided.
+ERROR_NO_OPEN_DOCUMENT=There is no open document.
 ERROR_NO_OPEN_DOCUMENT_COMPARE=There is no open document. Nothing to compare with.
 ERROR_ONLY_OPEN_ONE_FILE=You can only open one file!
 ERROR_OPENING_FILE=Error opening file: %s