@Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        PCollectionsImmutableMap<?, ?> that = (PCollectionsImmutableMap<?, ?>) o;
        return underlying().equals(that.underlying());
    }
@param key the key
@param value the value
@return a wrapped hash-based persistent map that has a single mapping
@param <K> the key type
@param <V> the value type
server-common/src/main/java/org/apache/kafka/server/immutable/pcollections/PCollectionsImmutableMap.java