/// tip

The next sections are **not necessarily "advanced"**.

And it's possible that for your use case, the solution is in one of them.

///

## Read the Tutorial first { #read-the-tutorial-first }

  }

  @CollectionFeature.Require({SUPPORTS_ADD, FAILS_FAST_ON_CONCURRENT_MODIFICATION})
  public void testSetCountZeroToOneConcurrentWithEntrySetIteration() {
    Iterator<Entry<E>> iterator = getMultiset().entrySet().iterator();
    assertSetCount(e3(), 1);
    assertThrows(ConcurrentModificationException.class, iterator::next);
  }

     */
    boolean isIntermediate();

    /**
     * Combine this referral with another to form a chain
     *
     * @param next the referral to combine with
     * @return new referral, combining a chain of referrals
     */
    DfsReferralDataInternal combine(DfsReferralData next);

    /**
     * Append another referral to this referral chain
     *
     * @param dr the referral to append
     */

                return true;
            }
        }
        return false;
    }

    @Override
    public E next() {
        if (!hasNext()) {
            throw new NoSuchElementException();
        }
        return iterators[index].next();
    }

    @Override
    public void remove() {
        throw new ClUnsupportedOperationException("remove");
    }

                        public boolean hasNext() {
                            return false;
                        }

                        @Override
                        public Entry<Object, Object> next() {
                            throw new NoSuchElementException();
                        }
                    };
                }

                @Override
                public int size() {

set maven.installation.conf default ${maven.conf}

[plexus.core]
load       ${maven.conf}/logging
optionally ${maven.home}/lib/ext/redisson/*.jar
optionally ${maven.home}/lib/ext/hazelcast/*.jar
optionally ${user.home}/.m2/ext/*.jar
optionally ${maven.home}/lib/ext/*.jar
load       ${maven.home}/lib/maven-*.jar

    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;

///

/// info

In this example we use invented custom headers `X-Key` and `X-Token`.

But in real cases, when implementing security, you would get more benefits from using the integrated [Security utilities (the next chapter)](../security/index.md){.internal-link target=_blank}.

///

## Dependencies errors and return values { #dependencies-errors-and-return-values }

You can use the same dependency *functions* you use normally.

  // http://gee.cs.oswego.edu/cgi-bin/viewcvs.cgi/jsr166/src/main/java/util/concurrent/

  /** The queued items */
  final E[] items;

  /** items index for next take, poll or remove */
  int takeIndex;

  /** items index for next put, offer, or add. */
  int putIndex;

  /** Number of items in the queue */
  private int count;

  /*
   * Concurrency control uses the classic two-condition algorithm

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.