xmerge: use String.length()==0 instead of String.equals(empty string)

Change-Id: I41b64c2dccad41193e15b6be2e62ce9dd63e0c3a
Reviewed-on: https://gerrit.libreoffice.org/11358Reviewed-by: Thomas Arnhold <thomas@arnhold.org>
Tested-by: Thomas Arnhold <thomas@arnhold.org>

xmerge/source/xmerge/java/org/openoffice/xmerge/converter/xml/xslt/DocumentDeserializerImpl.java

@@ -105,7 +105,7 @@ public final class DocumentDeserializerImpl
 
     public Source resolve(String href, String base) throws TransformerException {
         if (href != null) {
-            if (href.equals("javax.xml.transform.dom.DOMSource") || href.equals("")) {
+            if (href.equals("javax.xml.transform.dom.DOMSource") || href.length() == 0) {
                 return null;
             }
             try {

xmerge/source/xmerge/java/org/openoffice/xmerge/converter/xml/xslt/DocumentSerializerImpl.java

@@ -200,7 +200,7 @@ public final class DocumentSerializerImpl
     public Source resolve(String href, String base)
             throws TransformerException {
         if (href != null) {
-            if (href.equals("javax.xml.transform.dom.DOMSource") || href.equals("")) {
+            if (href.equals("javax.xml.transform.dom.DOMSource") || href.length() == 0) {
                 return null;
             }
             try {