Release Note: Enable XML Signature Secure Validation Mode by Default

The XML Signature secure validation mode has been enabled by default (previously it was not enabled by default unless running with a security manager). When enabled, validation of XML signatures are subject to stricter checking of algorithms and other constraints as specified by the `jdk.xml.dsig.secureValidationPolicy` security property.

If necessary, and at their own risk, applications can disable the mode by setting the `org.jcp.xml.dsig.secureValidation` property to `Boolean.FALSE` with the `DOMValidateContext.setProperty()` API.