Empty properties causing extra indents in XmlHandler

Minor fix to move down the code that increments the indent level in XmlHandler.showProperty - when Utils.isPropertyEmpty is true, it indents unnecessarily causing misalignment in the XML.

jhove-core/src/main/java/edu/harvard/hul/ois/jhove/handler/XmlHandler.java

@@ -744,18 +744,18 @@ protected String valueToString(Object obj) {
     }
 
     protected void showProperty(Property property) {
-        String margin = getIndent(++_level);
-        String margn2 = margin + " ";
-        String margn3 = margn2 + " ";
-        String margn4 = margn3 + " ";
-
         PropertyArity arity = property.getArity();
         PropertyType type = property.getType();
 
         // If the property would generate an empty element, don't output it,
         // as this could result in a schema violation.
         if (Utils.isPropertyEmpty(property, arity))
             return;
+
+        String margin = getIndent(++_level);
+        String margn2 = margin + " ";
+        String margn3 = margn2 + " ";
+        String margn4 = margn3 + " ";
 
         boolean valueIsProperty = PropertyType.PROPERTY.equals(type);
         boolean valueIsNiso = PropertyType.NISOIMAGEMETADATA.equals(type);