import com.google.common.collect.ForwardingObject;
import com.google.common.collect.Iterables;
import com.google.common.testing.ForwardingWrapperTester;
import java.lang.reflect.Method;
import java.util.Arrays;

/**
 * Tester for typical subclass of {@link ForwardingObject} by using Mockito.
 *
 * @author Ben Yu
 */
final class ForwardingObjectTester {

  private static final Method DELEGATE_METHOD;

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.ConcurrentMap;
import junit.framework.Assert;
import org.checkerframework.checker.nullness.qual.Nullable;

/**

 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.artifact.resolver.filter;

import java.util.Arrays;

import org.junit.jupiter.api.Test;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertTrue;

      return;
    }
    this.firstEntry = ENDPOINT;
    this.lastEntry = ENDPOINT;
    // Either both arrays are null or neither is, but we check both to satisfy the nullness checker.
    if (predecessor != null && successor != null) {
      Arrays.fill(predecessor, 0, size(), 0);
      Arrays.fill(successor, 0, size(), 0);
    }
    super.clear();
  }

  /*

import com.google.common.annotations.J2ktIncompatible;
import com.google.common.annotations.VisibleForTesting;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Arrays;
import java.util.LinkedHashMap;
import java.util.Map;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.graph;

import java.util.Arrays;
import java.util.Collection;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameters;

/** Tests for an undirected {@link StandardMutableGraph}. */

    assertThat((long) arraysDim1 * arraysDim2).isNotEqualTo((long) (arraysDim1 * arraysDim2));

    boolean[][] arrays = new boolean[arraysDim1][];
    // it's shared to avoid using too much memory in tests
    boolean[] sharedArray = new boolean[arraysDim2];
    Arrays.fill(arrays, sharedArray);

    try {
      Booleans.concat(arrays);
      fail();
    } catch (IllegalArgumentException expected) {
    }
  }

    File asciiFile = getTestFile("ascii.txt");
    File i18nFile = getTestFile("i18n.txt");
    assertTrue(Arrays.equals(ASCII.getBytes(US_ASCII), Files.toByteArray(asciiFile)));
    assertTrue(Arrays.equals(I18N.getBytes(UTF_8), Files.toByteArray(i18nFile)));
    assertTrue(Arrays.equals(I18N.getBytes(UTF_8), Files.asByteSource(i18nFile).read()));
  }

            return isLeft ? 1 : -1;
        }

        value = FILTER_1.matcher(value).replaceAll("");

        List<String> valueTokens = new ArrayList<>(Arrays.asList(FILTER_2.split(value)));
        List<String> rangeValueTokens = new ArrayList<>(Arrays.asList(FILTER_3.split(rangeValue.value)));

        addZeroTokens(valueTokens, 3);
        addZeroTokens(rangeValueTokens, 3);

        for (int i = 0; i < 3; i++) {

<div class="screenshot">
<img src="/img/tutorial/separate-openapi-schemas/image02.png">
</div>

This means that it will **always have a value**, it's just that sometimes the value could be `None` (or `null` in JSON).

That means that, clients using your API don't have to check if the value exists or not, they can **assume the field will always be there**, but just that in some cases it will have the default value of `None`.