Fix: xsl-stylesheet didn't have any practical effect.

TODO associated stylesheet is detected as a side effect of fetching the
source. Need to make sure this has been done when we call
getTransformer(). We also need a test here.

src/main/java/info/textgrid/services/aggregator/html/HTMLWriter.java

@@ -176,6 +176,7 @@ void detectEmbeddedStylesheet(final Source source) {
 					.getAssociatedStylesheet(source, null, null, null);
 			this.associatedStylesheetURI = Optional.of(new URI(
 					associatedStylesheet.getSystemId()));
+			logger.log(Level.INFO, "Detected associated stylesheet {0}, URI {1}", new Object[] { associatedStylesheet, associatedStylesheetURI.get()});
 
 		} catch (final TransformerConfigurationException e) {
 			logger.log(Level.WARNING, "Failed to load stylesheet from <?xsl-stylesheet?> declaration", e);
@@ -304,7 +305,8 @@ public ResponseBuilder createResponse() throws ObjectNotFoundFault, MetadataPars
 		if (isNotModified())
 			return getResponseBuilder();
 
-		getTransformer().setSource(getSource());
+		final Source source = getSource();
+		getTransformer().setSource(source);
 
 		if (requestedMediaType.isPresent()) {
 			setMediaType(requestedMediaType.get());