Only set setIsInSignedContent when we're inside the signed content, fix some NPEs (#666)
The Apache Santuario™ project is aimed at providing implementation of the primary security standards for XML:
This repository contains the Apache XML Security for Java subproject of Apache Santuario. This library includes the standard JSR-105 (Java XML Digital Signature) API, a mature DOM-based implementation of both XML Signature and XML Encryption, as well as a more recent StAX-based (streaming) XML Signature and XML Encryption implementation.