public void testPutAbsentConcurrentWithEntrySetIteration() {
    assertThrows(
        ConcurrentModificationException.class,
        () -> {
          Iterator<Entry<K, V>> iterator = getMap().entrySet().iterator();
          put(e3());
          iterator.next();
        });
  }

  @MapFeature.Require({FAILS_FAST_ON_CONCURRENT_MODIFICATION, SUPPORTS_PUT})
  @CollectionSize.Require(absent = ZERO)

For example, when using GraphQL you normally perform all the actions using only `POST` operations.

///

### Step 4: define the **path operation function** { #step-4-define-the-path-operation-function }

This is our "**path operation function**":

* **path**: is `/`.
* **operation**: is `get`.
* **function**: is the function below the "decorator" (below `@app.get("/")`).

{* ../../docs_src/first_steps/tutorial001.py hl[7] *}

import java.util.Iterator;
import java.util.NoSuchElementException;

import org.codelibs.core.exception.ClUnsupportedOperationException;

/**
 * An {@link Iterator} that returns a single value.
 *
 * @author koichik
 * @param <E> the element type
 */
public class SingleValueIterator<E> implements Iterator<E> {

    /** The only value returned by the iterator. */
    protected final E value;

  public int hashCode() {
    return Sets.hashCodeImpl(this);
  }

  // This declaration is needed to make Set.iterator() and
  // ImmutableCollection.iterator() appear consistent to javac's type inference.
  @Override
  public abstract UnmodifiableIterator<E> iterator();

  abstract static class CachingAsList<E> extends ImmutableSet<E> {
    @LazyInit private transient ImmutableList<E> asList;

    @Override

    Iterator<Entry<K, V>> iterator = multimap().entries().iterator();
    assertEquals(mapEntry(k0(), v0()), iterator.next());
    iterator.remove();
    assertTrue(multimap().isEmpty());
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testEntriesRemainValidAfterRemove() {
    Iterator<Entry<K, V>> iterator = multimap().entries().iterator();

  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testIteratorRemove_unsupported() {
    Iterator<E> iterator = collection.iterator();
    iterator.next();
    assertThrows(UnsupportedOperationException.class, iterator::remove);
    expectUnchanged();
    assertTrue(collection.contains(e0()));
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)

   * that approach would not lead to an infinite loop.
   *
   * @since 7.0
   */
  protected @Nullable V standardRemove(@Nullable Object key) {
    Iterator<Entry<K, V>> entryIterator = entrySet().iterator();
    while (entryIterator.hasNext()) {
      Entry<K, V> entry = entryIterator.next();
      if (Objects.equals(entry.getKey(), key)) {
        V value = entry.getValue();
        entryIterator.remove();

      @ParametricNullness E a, @ParametricNullness E b, @ParametricNullness E c, E... rest) {
    return forwardOrder.max(a, b, c, rest);
  }

  @Override
  public <E extends T> E min(Iterator<E> iterator) {
    return forwardOrder.max(iterator);
  }

  @Override
  public <E extends T> E min(Iterable<E> iterable) {
    return forwardOrder.max(iterable);
  }

  @Override

        @Override
        public Set<Entry<Object, Object>> entrySet() {
            return new AbstractImmutableSet<>() {
                @Override
                public Iterator<Entry<Object, Object>> iterator() {
                    return new Iterator<>() {
                        @Override
                        public boolean hasNext() {
                            return false;
                        }

        final List methods = (List) getHeaderFields0().get(authHeader);
        if (methods == null) {
            return null;
        }
        final Iterator iterator = methods.iterator();
        while (iterator.hasNext()) {
            final String currentAuthMethod = (String) iterator.next();
            if (currentAuthMethod.startsWith("NTLM")) {
                if (currentAuthMethod.length() == 4) {
                    authMethod = "NTLM";