protected String getClassName(long classId) {
        ClassRef cls = jfr.classes.get(classId);
        if (cls == null) {
            return "null";
        }
        byte[] className = jfr.symbols.get(cls.name);

        int arrayDepth = 0;
        while (className[arrayDepth] == '[') {
            arrayDepth++;
        }

        String name = toJavaClassName(className, arrayDepth);
        while (arrayDepth-- > 0) {
            name = name.concat("[]");
        }
        return name;
    }
JFRConverter is copied from one.jfr.JfrConverter. Because need to
add collectMultiEvents and getEventAggregator methods, to parse 
and process multiple events at one time.
oap-server/server-library/library-async-profiler-jfr-parser/src/main/java/one/jfr/JFRConverter.java