fix typo

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1866213 13f79535-47bb-0310-9956-ffa450edef68

src/ooxml/java/org/apache/poi/poifs/crypt/dsig/OOXMLURIDereferencer.java

@@ -69,7 +69,7 @@ public class OOXMLURIDereferencer implements URIDereferencer, SignatureConfigura
             throw new NullPointerException("URIReference cannot be null");
         }
         if (null == context) {
-            throw new NullPointerException("XMLCrytoContext cannot be null");
+            throw new NullPointerException("XMLCryptoContext cannot be null");
         }
 
         URI uri;