private String message(SAXParseException e) {
            String sourceId = e.getPublicId() == null ? "" : e.getPublicId();
            return "Invalid XML" + (sourceId.isEmpty() ? " (unknown source)" : " in " + sourceId) +
                    ": " + Exceptions.toMessageString(e) +
                    " [" + e.getLineNumber() + ":" + e.getColumnNumber() + "]";
        }
Error handler which will output name of source for warnings and errors
config-model/src/main/java/com/yahoo/config/model/builder/xml/XmlHelper.java