* @since 18.0 (since 3.0 as {@code Objects.firstNonNull()}).
   */
  public static <T> T firstNonNull(@CheckForNull T first, @CheckForNull T second) {
    if (first != null) {
      return first;
    }
    if (second != null) {
      return second;
    }
    throw new NullPointerException("Both parameters are null");
  }

  /**
   * Creates an instance of {@link ToStringHelper}.
   *

   * @param second the second array of elements to concatenate
   * @param type the component type of the returned array
   */
  @GwtIncompatible // Array.newInstance(Class, int)
  public static <T extends @Nullable Object> T[] concat(
      T[] first, T[] second, Class<@NonNull T> type) {
    T[] result = newArray(type, first.length + second.length);
    arraycopy(first, 0, result, 0, first.length);

    TestCallable secondCallable = new TestCallable(SettableFuture.<Void>create());
    Future<?> second = serializer.submitAsync(secondCallable, directExecutor());
    assertThat(secondCallable.called).isFalse();
    assertThat(second.toString()).contains(secondCallable.toString());
    firstFuture.set(null);
    assertThat(second.toString()).contains(secondCallable.future.toString());
  }

		if terr != nil {
			t.Errorf("failed to accept new connection. %v", terr)
			return
		}
		deadlineconn := New(tcpConn)
		deadlineconn.WithReadDeadline(time.Second)
		deadlineconn.WithWriteDeadline(time.Second)
		defer deadlineconn.Close()

		// Read a line
		b := make([]byte, 12)
		_, terr = deadlineconn.Read(b)
		if terr != nil {
			t.Errorf("failed to read from client. %v", terr)
			return

      if (iter != fdef.ret().end()) {
        const auto& v = a_edges.insert({iter->second, arg.name()});
        ASSERT_TRUE(v.second) << "Duplicate edge " << iter->second << " -> "
                              << arg.name() << ". fdef: " << fdef.DebugString();
      } else {
        const auto& v = a_edges.insert({arg.name(), arg.name()});
        ASSERT_TRUE(v.second) << "Duplicate edge " << arg.name() << " -> "

                .insert(EncodeTensorNameSlice(
                    string(v2_reader_->key()) /* full var's name */,
                    TensorSlice(slice_proto)))
                .second);
    }
  }

  // Second pass: adds the entries, ignoring the filtered keys.
  std::unique_ptr<TensorSliceReader::VarToShapeMap> var_to_shape_map(
      new TensorSliceReader::VarToShapeMap);

            });
    }

    private static <T> Map<AccessorKey, T> diff(Map<AccessorKey, T> first, Map<AccessorKey, T> second) {
        return first.entrySet().stream()
            .filter(e -> !second.containsKey(e.getKey()))
            .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
    }

```Python
old_dict = {
    "old key": "old value",
    "second old key": "second old value",
}
new_dict = {**old_dict, "new key": "new value"}
```

📥, `new_dict` 🔜 🔌 🌐 🔑-💲 👫 ⚪️➡️ `old_dict` ➕ 🆕 🔑-💲 👫:

```Python
{
    "old key": "old value",
    "second old key": "second old value",
    "new key": "new value",
}
```

  // object refers to a metric describing a single kubernetes object
  // (for example, hits-per-second on an Ingress object).
  // +optional
  optional ObjectMetricSource object = 2;

  // pods refers to a metric describing each pod in the current scale target
  // (for example, transactions-processed-per-second).  The values will be
  // averaged together before being compared to the target value.
  // +optional

	driveCountMD = NewGaugeMD(driveCount,
		"Count of all drives")

	// iostat related
	driveReadsPerSecMD = NewGaugeMD(driveReadsPerSec,
		"Reads per second on a drive",
		allDriveLabels...)
	driveReadsKBPerSecMD = NewGaugeMD(driveReadsKBPerSec,
		"Kilobytes read per second on a drive",
		allDriveLabels...)
	driveReadsAwaitMD = NewGaugeMD(driveReadsAwait,
		"Average time for read requests served on a drive",
		allDriveLabels...)