public void add(Fetch<K, V> fetch) {
        Objects.requireNonNull(fetch);
        addRecords(fetch.records);
        this.positionAdvanced |= fetch.positionAdvanced;
    }
Add another {@link Fetch} to this one; all of its records will be added to this fetch's
{@link #records() records}, and if the other fetch
{@link #positionAdvanced() advanced the consume position for any topic partition},
this fetch will be marked as having advanced the consume position as well.
@param fetch the other fetch to add; may not be null
clients/src/main/java/org/apache/kafka/clients/consumer/internals/Fetch.java