Allow START_DOCUMENT for XMLSecurityStreamReader

git-svn-id: https://svn.apache.org/repos/asf/santuario/xml-security-java/trunk@1856221 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/src/main/java/org/apache/xml/security/stax/impl/XMLSecurityStreamReader.java b/src/main/java/org/apache/xml/security/stax/impl/XMLSecurityStreamReader.java
index 7d6f3d9..e371c5b 100644
--- a/src/main/java/org/apache/xml/security/stax/impl/XMLSecurityStreamReader.java
+++ b/src/main/java/org/apache/xml/security/stax/impl/XMLSecurityStreamReader.java
@@ -167,6 +167,7 @@
                 case SPACE:
                 case COMMENT:
                 case PROCESSING_INSTRUCTION:
+                case START_DOCUMENT:
                     continue;
                 case CDATA:
                 case CHARACTERS: