@Override
        public String generate(String name, boolean negated) {
            if (negated) {
                return String.format("%s != null", name);
            } else {
                return String.format("%s == null", name);
            }
        }
For versions of a field that are nullable, IsNullCondition creates a null check.
generator/src/main/java/org/apache/kafka/message/IsNullConditional.java