private String stackTrace(Throwable throwable) {
        StringWriter writer = new StringWriter();
        PrintWriter wrappedWriter = new PrintWriter(writer);
        throwable.printStackTrace(wrappedWriter);
        wrappedWriter.close();
        return writer.toString();
    }
Un-escapes previously escaped string.
note: look at com.yahoo.config.StringNode.unescapeQuotedString()

@param s String that might need un-escaping
@return Returns un-escaped string
vespalog/src/main/java/com/yahoo/log/VespaFormatter.java