public static String className(Object o) {
        return o != null ? o.getClass().getName() : "null";
    }
Get the class name for an object in a null-safe manner.
@param o the object whose class name is to be returned
@return "null" if the object is null; or else the object's class name
connect/runtime/src/main/java/org/apache/kafka/connect/util/ConnectUtils.java