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SDK to implement Numaflow Source or User Defined Functions or Sinks in Java.

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package io.numaproj.numaflow.sinker;

/**
 * An iterator over a collection of {@link Datum} elements.
 * Passed to {@link Sinker#processMessages(DatumIterator)} method.
 */
public interface DatumIterator {

    /**
     * Returns the next element in the iterator
     * This method blocks until an element becomes available in the queue.
     * When EOF_DATUM is received, this method will return null and the iterator will be closed.
     *
     * @return the next element in the iterator, null if EOF_DATUM is received or the iterator is already closed
     *
     * @throws InterruptedException if the thread is interrupted while waiting for the next element
     */
    Datum next() throws InterruptedException;
}