* that traverses the elements in {@code a}, followed by the elements in {@code b}. The source
   * iterators are not polled until necessary.
   *
   * <p>The returned iterable's iterator supports {@code remove()} when the corresponding input
   * iterator supports it.
   *
   * <p><b>{@code Stream} equivalent:</b> {@link Stream#concat}.
   *
   * @since 20.0
   */
  public static <T extends @Nullable Object> FluentIterable<T> concat(

So, even with the code above that doesn't use Pydantic explicitly, FastAPI is using Pydantic to convert those standard dataclasses to Pydantic's own flavor of dataclasses.

And of course, it supports the same:

* data validation
* data serialization
* data documentation, etc.

  }

  @Override
  protected Collection<Method> suppressForConcurrentHashMap() {
    /*
     * The entrySet() of ConcurrentHashMap, unlike that of other Map
     * implementations, supports add() under JDK8. This seems problematic, but I
     * didn't see that discussed in the review, which included many other
     * changes: https://mail.openjdk.org/pipermail/core-libs-dev/2013-May/thread.html#17367
     *

   * elements in {@code a}, followed by the elements in {@code b}. The source iterators are not
   * polled until necessary.
   *
   * <p>The returned iterator supports {@code remove()} when the corresponding input iterator
   * supports it.
   */
  public static <T extends @Nullable Object> Iterator<T> concat(
      Iterator<? extends T> a, Iterator<? extends T> b) {
    checkNotNull(a);
    checkNotNull(b);

		predCount++
	}
	if f.ObjectSizeLessThan != 0 {
		pType = sizeLtPred
		predCount++
	}
	// Note: S3 supports empty <Filter></Filter>, so predCount == 0 is
	// valid.
	if predCount > 1 {
		return errInvalidFilter
	}

	var err error
	switch pType {
	case nonePred:
	// S3 supports empty <Filter></Filter>
	case prefixPred:
	case andPred:
		err = f.And.Validate()
	case tagPred:

			}
			if h.Typeflag == TypeGNUSparse {
				whyOnlyGNU = "only GNU supports TypeGNUSparse"
				format.mayOnlyBe(FormatGNU)
			} else {
				whyNoGNU = "GNU supports sparse files only with TypeGNUSparse"
				format.mustNotBe(FormatGNU)
			}
			whyNoUSTAR = "USTAR does not support sparse files"
			format.mustNotBe(FormatUSTAR)
		}
	*/

	// Check desired format.

   * that it can be done securely, without vulnerability to race conditions (i.e. when the file
   * system does not support {@link SecureDirectoryStream}).
   *
   * <p><b>Warning:</b> On a file system that supports symbolic links, it is possible for an
   * insecure recursive delete to delete files and directories that are <i>outside</i> the directory

   * changes the contents of the transposed table and vice versa.
   *
   * <p>The returned table supports update operations as long as the input table supports the
   * analogous operation with swapped rows and columns. For example, in a {@link HashBasedTable}
   * instance, {@code rowKeySet().iterator()} supports {@code remove()} but {@code
   * columnKeySet().iterator()} doesn't. With a transposed {@link HashBasedTable}, it's the other

   * that it can be done securely, without vulnerability to race conditions (i.e. when the file
   * system does not support {@link SecureDirectoryStream}).
   *
   * <p><b>Warning:</b> On a file system that supports symbolic links, it is possible for an
   * insecure recursive delete to delete files and directories that are <i>outside</i> the directory

     */
    public void setUsername(final String userName) {
        this.username = userName;
    }

    /**
     * Get the passphrase of the private key file. The passphrase is used only when host/protocol supports
     * authentication via exchange of private/public keys and private key was used for authentication.
     *
     * @return passphrase of the private key file
     */
    public String getPassphrase() {