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

Change-Id: Id38f28e7138460493fde982cc1ebc75c3cb0b386
Reviewed-on: https://gerrit.libreoffice.org/11365Reviewed-by: Thomas Arnhold <thomas@arnhold.org>
Tested-by: Thomas Arnhold <thomas@arnhold.org>

toolkit/qa/complex/toolkit/accessibility/_XAccessibleText.java

@@ -629,7 +629,7 @@ public class _XAccessibleText {
                 System.out.println("getTextRange(0, 0): ");
                 txtRange = oObj.getTextRange(0, 0);
                 System.out.println(txtRange);
-                locRes = txtRange.equals("");
+                locRes = txtRange.length() == 0;
                 res &= locRes;
                 if (!locRes) {
                     System.out.println("Empty string was expected");