Iterator<Entry<K, Collection<V>>> entryIterator = unfiltered.asMap().entrySet().iterator();
    boolean changed = false;
    while (entryIterator.hasNext()) {
      Entry<K, Collection<V>> entry = entryIterator.next();
      K key = entry.getKey();
      Collection<V> collection = filterCollection(entry.getValue(), new ValuePredicate(key));
      if (!collection.isEmpty()

            assertEquals(second, referralData.next());
            assertEquals(referralData, second.next());

            referralData.append(third);
            assertEquals(third, referralData.next());
            assertEquals(second, third.next());
            assertEquals(referralData, second.next());
        }

        @Test
        @DisplayName("Should handle next() correctly")
        void testNext() {

            @Override
            protected @Nullable N computeNext() {
              while (nodeConnections.hasNext()) {
                NodeConnection<N> nodeConnection = nodeConnections.next();
                boolean added = seenNodes.add(nodeConnection.node);
                if (added) {
                  return nodeConnection.node;
                }
              }
              return endOfData();

    Iterator<T> iteratorA = iterableA.iterator();
    Iterator<T> iteratorB = iterableB.iterator();

    while (iteratorA.hasNext() && iteratorB.hasNext()) {
      if (!elementEquivalence.equivalent(iteratorA.next(), iteratorB.next())) {
        return false;
      }
    }

    return !iteratorA.hasNext() && !iteratorB.hasNext();
  }

  @Override
  protected int doHash(Iterable<T> iterable) {
    int hash = 78721;

       * initialized by next() -- which initializes rowEntry, too.
       *
       * - rowEntry isn't cleared except below. If it was cleared below, then either
       *   columnIterator.remove() would have failed above (if the user hasn't called next() since
       *   then) or rowEntry would have been initialized by next() (as discussed above).
       */

    }

    /**
     * Checks if a next page exists.
     *
     * @return true if next page exists, false otherwise
     */
    public boolean isExistNextPage() {
        return existNextPage;
    }

    /**
     * Sets the flag indicating if a next page exists.
     *
     * @param existNextPage true if next page exists, false otherwise
     */

        this.existPrePage = existPrePage;
    }

    /**
     * Checks if a next page exists.
     * @return true if a next page exists, false otherwise.
     */
    public boolean isExistNextPage() {
        return existNextPage;
    }

    /**
     * Sets whether a next page exists.
     * @param existNextPage true if a next page exists, false otherwise.
     */

    }

    /**
     * Checks if there is a next page available.
     *
     * @return true if next page exists, false otherwise
     */
    public boolean isExistNextPage() {
        return existNextPage;
    }

    /**
     * Sets whether there is a next page available.
     *
     * @param existNextPage true if next page exists, false otherwise
     */

But first, let's check some small concepts.

## In a hurry? { #in-a-hurry }

If you don't care about any of these terms and you just need to add security with authentication based on username and password *right now*, skip to the next chapters.

## OAuth2 { #oauth2 }

OAuth2 is a specification that defines several ways to handle authentication and authorization.

It is quite an extensive specification and covers several complex use cases.

    }

    @Override
    public int encode(byte[] dst, int dstIndex) {
        int start = dstIndex;

        // Write context header
        SMBUtil.writeInt4(0, dst, dstIndex); // Next (offset to next context, 0 for last)
        dstIndex += 4;

        SMBUtil.writeInt2(16, dst, dstIndex); // NameOffset (from start of context)
        dstIndex += 2;

        SMBUtil.writeInt2(4, dst, dstIndex); // NameLength