Optional<K> getKey(V value) {
            return Optional.ofNullable(reverseMap.get(value));
        }
Helper class which maintains a bi-directional mapping from a key to a set of values.
Each value can map to one and only one key, but many values can be associated with
a single key.

@param <K> The key type
@param <V> The value type
clients/src/main/java/org/apache/kafka/clients/admin/internals/AdminApiDriver.java