import java.util.Iterator;
import java.util.List;
import org.jspecify.annotations.Nullable;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests addAll operations on a collection. Can't be invoked directly;
 * please see {@link com.google.common.collect.testing.CollectionTestSuiteBuilder}.
 *
 * @author Chris Povirk
 * @author Kevin Bourrillion
 */
@GwtCompatible

		"#define A (x) \n" + "A\n",
		"(.x.).\n",
	},
	{
		"macro with arguments",
		"#define A(x, y, z) x+z+y\n" + "A(1, 2, 3)\n",
		"1.+.3.+.2.\n",
	},
	{
		"argumented macro invoked without arguments",
		lines(
			"#define X() foo ",
			"X()",
			"X",
		),
		"foo.\n.X.\n",
	},
	{
		"multiline macro without arguments",
		lines(
			"#define A 1\\",
			"\t2\\",
			"\t3",

import java.util.Collections;
import java.util.List;
import java.util.Map.Entry;
import java.util.NavigableMap;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests operations on a NavigableMap. Can't be invoked directly; please
 * see {@code NavigableMapTestSuiteBuilder}.
 *
 * @author Jesse Wilson
 * @author Louis Wasserman
 */
@GwtIncompatible

import java.util.Iterator;
import java.util.List;
import java.util.NavigableSet;
import java.util.TreeSet;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests operations on a NavigableSet. Can't be invoked directly; please
 * see {@code NavigableSetTestSuiteBuilder}.
 *
 * @author Jesse Wilson
 * @author Louis Wasserman
 */
@GwtIncompatible

import java.util.Collections;
import java.util.List;
import java.util.Map.Entry;
import java.util.NavigableMap;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests operations on a NavigableMap. Can't be invoked directly; please
 * see {@code NavigableMapTestSuiteBuilder}.
 *
 * @author Jesse Wilson
 * @author Louis Wasserman
 */
@GwtIncompatible

import java.util.List;
import java.util.Map.Entry;
import java.util.NoSuchElementException;
import java.util.SortedMap;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests operations on a SortedMap. Can't be invoked directly; please see
 * {@code SortedMapTestSuiteBuilder}.
 *
 * @author Jesse Wilson
 * @author Louis Wasserman
 */
@GwtCompatible

import java.util.AbstractSet;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@code removeAll} operations on a collection. Can't be invoked
 * directly; please see {@link com.google.common.collect.testing.CollectionTestSuiteBuilder}.
 *
 * @author George van den Driessche
 * @author Chris Povirk
 */
@GwtCompatible

   *     escaped for any other reason
   */
  public abstract String escape(String string);

  private final Function<String, String> asFunction = this::escape;

  /** Returns a {@link Function} that invokes {@link #escape(String)} on this escaper. */
  public final Function<String, String> asFunction() {
    return asFunction;
  }

            !item.equals(item.toString()));
      }
    }
  }

  /**
   * Class used to test whether equals() correctly handles an instance of an incompatible class.
   * Since it is a private inner class, the invoker can never pass in an instance to the tester
   */
  private enum NotAnInstance {
    EQUAL_TO_NOTHING;
  }

## Die normale **FastAPI**-Anwendung

Sehen wir uns zunächst an, wie die normale API-Anwendung aussehen würde, bevor wir den Callback hinzufügen.

Sie verfügt über eine *Pfadoperation*, die einen `Invoice`-Body empfängt, und einen Query-Parameter `callback_url`, der die URL für den Callback enthält.

Dieser Teil ist ziemlich normal, der größte Teil des Codes ist Ihnen wahrscheinlich bereits bekannt: