scope: Optional string. Several scopes (each one a string) separated by spaces. E.g.
        "items:read items:write users:read profile openid"
    client_id: optional string. OAuth2 recommends sending the client_id and client_secret (if any)
        using HTTP Basic auth, as: client_id:client_secret
    client_secret: optional string. OAuth2 recommends sending the client_id and client_secret (if any)

            return Optional.of(Boolean.TRUE);
        }
        return Optional.empty();
    }

    @Override
    public Optional<Boolean> showVersion() {
        if (commandLine.hasOption(CLIManager.SHOW_VERSION)) {
            return Optional.of(Boolean.TRUE);
        }
        return Optional.empty();
    }

    @Override
    public Optional<Boolean> quiet() {

            @Nonnull
            @Override
            public Optional<Source> getInstallationToolchainsSource() {
                return Optional.ofNullable(installationToolchainsSource);
            }

            @Nonnull
            @Override
            public Optional<Source> getUserToolchainsSource() {
                return Optional.ofNullable(userToolchainsSource);
            }

            @Override

			Optional:    true,
			Type:        "csv",
		},
		config.HelpKV{
			Key:         AllowEncrypted,
			Description: `enable 'encryption' along with compression`,
			Optional:    true,
			Type:        "on|off",
		},
		config.HelpKV{
			Key:         config.Comment,
			Description: config.DefaultComment,
			Optional:    true,
			Type:        "sentence",
		},
	}

   *
   * <p><b>Java 9 users:</b> use {@code optional.stream()} instead.
   */
  @Beta
  @InlineMe(replacement = "optional.stream()")
  @InlineMeValidationDisabled("Java 9+ API only")
  public static <T> Stream<T> stream(java.util.Optional<T> optional) {
    return optional.isPresent() ? Stream.of(optional.get()) : Stream.empty();
  }

  /**
   * If a value is present in {@code optional}, returns a stream containing only that element,

@REM
@REM   JAVA_HOME           (Optional) Points to a Java installation.
@REM   MAVEN_BATCH_ECHO    (Optional) Set to 'on' to enable the echoing of the batch commands.
@REM   MAVEN_BATCH_PAUSE   (Optional) set to 'on' to wait for a key stroke before ending.
@REM   MAVEN_OPTS          (Optional) Java runtime options used when Maven is executed.
@REM   MAVEN_SKIP_RC       (Optional) Flag to disable loading of mavenrc files.

			Description: `set Content-Security-Policy response header value` + defaultHelpPostfix(browserCSPPolicy),
			Optional:    true,
			Type:        "string",
		},
		config.HelpKV{
			Key:         browserHSTSSeconds,
			Description: `set Strict-Transport-Security 'max-age' amount of seconds value` + defaultHelpPostfix(browserHSTSSeconds),
			Optional:    true,
			Type:        "number",
		},
		config.HelpKV{

from typing import Optional

from fastapi import FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()


class SubModel(BaseModel):
    a: Optional[str] = "foo"


class Model(BaseModel):
    x: Optional[int] = None
    sub: SubModel


class ModelSubclass(Model):
    y: int
    z: int = 0
    w: Optional[int] = None


class ModelDefaults(BaseModel):

			Optional:    true,
			Type:        "path",
			Sensitive:   true,
		},
		config.HelpKV{
			Key:         ClientCertKey,
			Description: `client cert key for mTLS authentication` + defaultHelpPostfix(ClientCertKey),
			Optional:    true,
			Type:        "path",
			Sensitive:   true,
		},
		config.HelpKV{
			Key:         config.Comment,
			Description: config.DefaultComment,
			Optional:    true,

   * @throws NullPointerException if any element in the stream is {@code null}.
   * @return {@code Optional.of(onlyElement)} if the stream has exactly one element (must not be
   *     {@code null}) and returns {@code Optional.empty()} if it has none.
   */
  @SuppressWarnings("unchecked")
  public static <T> Collector<T, ?, Optional<T>> toOptional() {
    return (Collector) TO_OPTIONAL;
  }