assertEquals(20, counter.read(new byte[30]));
    assertEquals(20, counter.getCount());
    assertEquals(-1, counter.read(new byte[30]));
    assertEquals(20, counter.getCount());
  }

  @SuppressWarnings("CheckReturnValue") // calling read() to skip a byte
  public void testMark() throws Exception {
    assertTrue(counter.markSupported());
    assertEquals(10, counter.read(new byte[10]));
    assertEquals(10, counter.getCount());

 *   <li>{@link MapMaker}
 *   <li>{@link MinMaxPriorityQueue}
 *   <li>{@link PeekingIterator}
 * </ul>
 */
@CheckReturnValue
@NullMarked
package com.google.common.collect;

import com.google.errorprone.annotations.CheckReturnValue;

        Java8Compatibility.clear(buffer);
      }
      return builder.toString();
    }
  }

  private static class UrlByteSourceFactory extends FileByteSourceFactory {

    @SuppressWarnings("CheckReturnValue") // only using super.createSource to create a file
    @Override
    public ByteSource createSource(byte[] bytes) throws IOException {
      super.createSource(bytes);

import com.google.common.annotations.J2ktIncompatible;
import com.google.common.collect.ForwardingObject;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.CheckReturnValue;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;

      assertTrue(Thread.holdsLock(mutex));
      return delegate.toArray(array);
    }

    private static final long serialVersionUID = 0;
  }

  @SuppressWarnings("CheckReturnValue")
  public void testHoldsLockOnAllOperations() {
    create().element();
    create().offer("foo");
    create().peek();
    create().poll();
    create().remove();
    create().add("foo");

  }

  /**
   * Tests that the ImmutableValueGraph.Builder doesn't change when the creating ValueGraphBuilder
   * changes.
   */
  @Test
  @SuppressWarnings("CheckReturnValue")
  public void immutableValueGraphBuilder_copiesGraphBuilder() {
    ValueGraphBuilder<String, Object> graphBuilder =
        ValueGraphBuilder.directed()
            .allowsSelfLoops(true)

  }

  /**
   * Tests that the ImmutableNetwork.Builder doesn't change when the creating NetworkBuilder
   * changes.
   */
  @Test
  @SuppressWarnings("CheckReturnValue")
  public void immutableNetworkBuilder_copiesNetworkBuilder() {
    NetworkBuilder<String, Object> networkBuilder =
        NetworkBuilder.directed()
            .allowsSelfLoops(true)

      assertTrue(Thread.holdsLock(mutex));
      return delegate.descendingIterator();
    }

    private static final long serialVersionUID = 0;
  }

  @SuppressWarnings("CheckReturnValue")
  public void testHoldsLockOnAllOperations() {
    create().element();
    create().offer("foo");
    create().peek();
    create().poll();
    create().remove();
    create().add("foo");

  }

  /**
   * Tests that the ImmutableValueGraph.Builder doesn't change when the creating ValueGraphBuilder
   * changes.
   */
  @Test
  @SuppressWarnings("CheckReturnValue")
  public void immutableValueGraphBuilder_copiesGraphBuilder() {
    ValueGraphBuilder<String, Object> graphBuilder =
        ValueGraphBuilder.directed()
            .allowsSelfLoops(true)

      assertTrue(Thread.holdsLock(mutex));
      return delegate.descendingIterator();
    }

    private static final long serialVersionUID = 0;
  }

  @SuppressWarnings("CheckReturnValue")
  public void testHoldsLockOnAllOperations() {
    create().element();
    create().offer("foo");
    create().peek();
    create().poll();
    create().remove();
    create().add("foo");