Replace <code> with {@code} in javadoc

{@code foo} is shorter and easier to read and write than
<code>foo</code>, which is why it was introduced years ago in the
javadoc processor.  Make consistent use of it throughout the
documentation comments.

Change-Id: I59d428cb6c5015453629398b0697891b83c8e91d

gerrit-gwtui/src/main/java/com/google/gerrit/client/ui/ComplexDisclosurePanel.java

@@ -108,7 +108,7 @@ public class ComplexDisclosurePanel extends Composite implements
   /**
    * Changes the visible state of this panel's content.
    *
-   * @param isOpen <code>true</code> to open, <code>false</code> to close
+   * @param isOpen {@code true} to open, {@code false} to close
    */
   public void setOpen(final boolean isOpen) {
     main.setOpen(isOpen);

gerrit-gwtui/src/main/java/com/google/gerrit/client/ui/FancyFlexTable.java

@@ -65,7 +65,7 @@ public abstract class FancyFlexTable<RowItem> extends Composite {
    * @param comparator comparator by which the items in the table are sorted
    * @param item the item that should be found
    * @return if the item is found the number of the row that contains the item;
-   *         if the item is not found <code>-1</code>
+   *         if the item is not found {@code -1}
    */
   protected int findRowItem(Comparator<RowItem> comparator, RowItem item) {
     int row = lookupRowItem(comparator, item);
@@ -84,7 +84,7 @@ public abstract class FancyFlexTable<RowItem> extends Composite {
    * @param item the new item that should be inserted
    * @return if the item is not yet contained in the table, the number of the
    *         row where the new item should be inserted; if the item is already
-   *         contained in the table <code>-1</code>
+   *         contained in the table {@code -1}
    */
   protected int getInsertRow(Comparator<RowItem> comparator, RowItem item) {
     int row = lookupRowItem(comparator, item);

gerrit-gwtui/src/main/java/com/google/gerrit/client/ui/FilteredUserInterface.java

@@ -19,7 +19,7 @@ public interface FilteredUserInterface {
    * Return the value by which the user interface is currently filtered.
    *
    * @return value by which the user interface is currently filtered,
-   *         <code>null</code> or empty String if currently no filter is applied
+   *         {@code null} or empty String if currently no filter is applied
    */
   public String getCurrentFilter();
 }

gerrit-gwtui/src/main/java/com/google/gerrit/client/ui/Hyperlink.java

@@ -44,7 +44,7 @@ public class Hyperlink extends com.google.gwt.user.client.ui.Hyperlink {
    * Creates a hyperlink with its text and target history token specified.
    *
    * @param text the hyperlink's text
-   * @param asHTML <code>true</code> to treat the specified text as html
+   * @param asHTML {@code true} to treat the specified text as html
    * @param token the history token to which it will link
    * @see #setTargetHistoryToken
    */