Using the Preview Legend feature on YSLD styles causes an XML parsing error
"Content is not allowed in prolog" since
org.geoserver.wms.web.data.StyleAdminPanel currently only handles SLD
styles:
StyleInfo si = new StyleInfoImpl(stylePage.getCatalog());
String styleName = "tmp" + UUID.randomUUID().toString();
String styleFileName = styleName + ".sld";
si.setFilename(styleFileName);
si.setName(styleName);
si.setWorkspace(stylePage.styleModel.getObject().getWorkspace());
Also, if a proxy base URL is set that is missing a slash at the end (e.g.,
"http://geoserver.org/geoserver" instead of
"http://geoserver.org/geoserver/"), then the Preview Legend would fail for
external legend images because it would build a URL like
"http://geoserver.org/geoserverstyles" instead of
"http://geoserver.org/geoserver/styles".
