}
    if (builder.getKeyStrength() == Strength.WEAK
        && builder.getValueStrength() == Strength.STRONG) {
      return new MapMakerInternalMap<>(builder, WeakKeyDummyValueEntry.Helper.<K>instance());
    }
    if (builder.getValueStrength() == Strength.WEAK) {
      throw new IllegalArgumentException("Map cannot have both weak and dummy values");
    }
    throw new AssertionError();
  }

    }
    if (builder.getKeyStrength() == Strength.WEAK
        && builder.getValueStrength() == Strength.STRONG) {
      return new MapMakerInternalMap<>(builder, WeakKeyDummyValueEntry.Helper.<K>instance());
    }
    if (builder.getValueStrength() == Strength.WEAK) {
      throw new IllegalArgumentException("Map cannot have both weak and dummy values");
    }
    throw new AssertionError();
  }

	}
	if _, err := buf.Peek(1); err != io.EOF {
		t.Fatalf("want EOF got %v", err)
	}

	// Test for issue 3022, not exposing a reader's error on a successful Peek.
	buf = NewReaderSize(dataAndEOFReader("abcd"), 32)
	if s, err := buf.Peek(2); string(s) != "ab" || err != nil {
		t.Errorf(`Peek(2) on "abcd", EOF = %q, %v; want "ab", nil`, string(s), err)
	}
	if s, err := buf.Peek(4); string(s) != "abcd" || err != nil {

    Iterator<String> nonpeek = Lists.newArrayList("a", "b", "c").iterator();
    PeekingIterator<String> peek = Iterators.peekingIterator(nonpeek);
    assertNotSame(peek, nonpeek);
    assertSame(peek, Iterators.peekingIterator(peek));
    assertSame(peek, Iterators.peekingIterator((Iterator<String>) peek));
  }

    Iterator<String> nonpeek = Lists.newArrayList("a", "b", "c").iterator();
    PeekingIterator<String> peek = Iterators.peekingIterator(nonpeek);
    assertNotSame(peek, nonpeek);
    assertSame(peek, Iterators.peekingIterator(peek));
    assertSame(peek, Iterators.peekingIterator((Iterator<String>) peek));
  }

   *     Iterators.peekingIterator(Iterators.forArray("a", "b"));
   * String a1 = peekingIterator.peek(); // returns "a"
   * String a2 = peekingIterator.peek(); // also returns "a"
   * String a3 = peekingIterator.next(); // also returns "a"
   * }</pre>
   *
   * <p>Any structural changes to the underlying iteration (aside from those performed by the

    edge-case regression introduced with the events cleanup in 3.14.0.

 *  Fix: Provide actionable advice when the exchange is non-null. Prior to 3.14, OkHttp would
    silently leak connections when an interceptor retries without closing the response body. With
    3.14 we detect this problem but the exception was not helpful.

## Version 3.14.0

_2019-03-14_

import com.google.common.collect.Maps.EntryTransformer;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.concurrent.LazyInit;
import com.google.j2objc.annotations.Weak;
import com.google.j2objc.annotations.WeakOuter;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.AbstractCollection;

   */
  @GwtIncompatible // java.lang.ref.WeakReference
  @CanIgnoreReturnValue
  public CacheBuilder<K, V> weakKeys() {
    return setKeyStrength(Strength.WEAK);
  }

  @CanIgnoreReturnValue
  CacheBuilder<K, V> setKeyStrength(Strength strength) {
    checkState(keyStrength == null, "Key strength was already set to %s", keyStrength);

   */
  @GwtIncompatible // java.lang.ref.WeakReference
  @CanIgnoreReturnValue
  public CacheBuilder<K, V> weakKeys() {
    return setKeyStrength(Strength.WEAK);
  }

  @CanIgnoreReturnValue
  CacheBuilder<K, V> setKeyStrength(Strength strength) {
    checkState(keyStrength == null, "Key strength was already set to %s", keyStrength);