[SANTUARIO-368] - NPE in XMLSignature

git-svn-id: https://svn.apache.org/repos/asf/santuario/xml-security-java/branches/1.5.x-fixes@1527501 13f79535-47bb-0310-9956-ffa450edef68
[SANTUARIO-368] - Updating Changelog

git-svn-id: https://svn.apache.org/repos/asf/santuario/xml-security-java/branches/1.5.x-fixes@1527502 13f79535-47bb-0310-9956-ffa450edef68