xmerge: String comparison

Change-Id: Icda2e693c1e0177708c83af8048bc4e56c0db4ce
Reviewed-on: https://gerrit.libreoffice.org/10665Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>

xmerge/source/xmerge/java/org/openoffice/xmerge/converter/xml/sxc/Format.java

@@ -434,7 +434,7 @@ public class Format implements Cloneable {
                 return false;
         }
 
-        if (fontName!=rhs.fontName)
+        if (fontName == null ? rhs.fontName != null : !fontName.equals(rhs.fontName))
             return false;
 
         if (foreground!=rhs.foreground)