@Override
        public void ensureValid(String name, Object value) {
            if (value == null) {
                // Pass in the string null to avoid the spotbugs warning
                throw new ConfigException(name, "null", "entry must be non null");
            }
        }
A numeric range that checks both the upper (inclusive) and lower bound
clients/src/main/java/org/apache/kafka/common/config/ConfigDef.java