Fix exception during applying policy

Author: MaximPlusov

core/pom.xml

@@ -86,6 +86,11 @@
       <scope>test</scope>
     </dependency>
 
+    <dependency>
+      <groupId>net.sf.saxon</groupId>
+      <artifactId>Saxon-HE</artifactId>
+    </dependency>
+
     <dependency>
       <groupId>com.fasterxml.jackson.core</groupId>
       <artifactId>jackson-databind</artifactId>

core/src/main/java/org/verapdf/policy/PolicyChecker.java

@@ -215,7 +215,8 @@ private static void applySchematronXsl(final InputStream schematronXsl, final In
 	}
 
 	private static TransformerFactory getTransformerFactory() {
-		TransformerFactory fact = TransformerFactory.newInstance();
+		TransformerFactory fact = TransformerFactory.newInstance("net.sf.saxon.TransformerFactoryImpl",
+				null);
 		try {
 			fact.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);
 			fact.setAttribute(XMLConstants.ACCESS_EXTERNAL_STYLESHEET, "file");

core/src/main/java/org/verapdf/policy/SchematronPipeline.java

@@ -90,7 +90,8 @@ private static File createTempFileResult(final Transformer transformer, final St
 	}
 
 	private static TransformerFactory getTransformerFactory() {
-		TransformerFactory fact = TransformerFactory.newInstance();
+		TransformerFactory fact = TransformerFactory.newInstance("net.sf.saxon.TransformerFactoryImpl",
+				null);
 		try {
 			fact.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);
 			fact.setAttribute(XMLConstants.ACCESS_EXTERNAL_STYLESHEET, "file");

core/src/main/java/org/verapdf/report/XsltTransformer.java

@@ -77,7 +77,8 @@ public static void transform(InputStream source, InputStream xslt, PrintWriter d
 	}
 
 	private static TransformerFactory getTransformerFactory() {
-		TransformerFactory fact = TransformerFactory.newInstance();
+		TransformerFactory fact = TransformerFactory.newInstance("net.sf.saxon.TransformerFactoryImpl",
+				null);
 		try {
 			fact.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);
 			fact.setAttribute(XMLConstants.ACCESS_EXTERNAL_STYLESHEET, "file");

pom.xml

@@ -189,6 +189,12 @@
         <version>2.3.0.1</version>
       </dependency>
 
+      <dependency>
+        <groupId>net.sf.saxon</groupId>
+        <artifactId>Saxon-HE</artifactId>
+        <version>12.8</version>
+      </dependency>
+
     </dependencies>
   </dependencyManagement>