[XMLBEANS-548] support adding standalone flag to xml declaration

git-svn-id: https://svn.apache.org/repos/asf/xmlbeans/trunk@1869599 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/src/store/org/apache/xmlbeans/impl/store/Saver.java b/src/store/org/apache/xmlbeans/impl/store/Saver.java
index 7250ed7..2f289b2 100755
--- a/src/store/org/apache/xmlbeans/impl/store/Saver.java
+++ b/src/store/org/apache/xmlbeans/impl/store/Saver.java
@@ -911,9 +911,16 @@
                 if (version == null)
                     version = "1.0";
 
+                Boolean standalone = null;
+                if (props != null && props.get(XmlDocumentProperties.STANDALONE) != null)
+                    standalone = Boolean.valueOf("yes".equals(props.get(XmlDocumentProperties.STANDALONE)));
+
                 emit("<?xml version=\"");
                 emit(version);
-                emit("\" encoding=\"" + encoding + "\"?>" + _newLine);
+                emit( "\" encoding=\"" + encoding + "\"");
+                if (standalone != null)
+                    emit( " standalone=\"" + (standalone.booleanValue() ? "yes" : "no") + "\"");
+                emit( "?>" + _newLine );
             }
         }