private static Validator embeddedValidator(final String keyPrefix, final Validator base) {
        if (base == null) return null;
        return new Validator() {
            public void ensureValid(String name, Object value) {
                base.ensureValid(name.substring(keyPrefix.length()), value);
            }

            @Override
            public String toString() {
                return base.toString();
            }
        };
    }
Returns a new validator instance that delegates to the base validator but unprefixes the config name along the way.
clients/src/main/java/org/apache/kafka/common/config/ConfigDef.java