Update DateTimeFormat documentation

- Remove an explicit default value parameter

src/Module/Api/ApiResponse.php

@@ -103,7 +103,7 @@ class ApiResponse extends Response
 			'alternate'    => $user_info['url'],
 			'self'         => $this->baseUrl . '/' . $this->args->getQueryString(),
 			'base'         => $this->baseUrl,
-			'updated'      => DateTimeFormat::utc(null, DateTimeFormat::API),
+			'updated'      => DateTimeFormat::utcNow(DateTimeFormat::API),
 			'atom_updated' => DateTimeFormat::utcNow(DateTimeFormat::ATOM),
 			'language'     => $user_info['lang'],
 			'logo'         => $this->baseUrl . '/images/friendica-32.png',

src/Security/OAuth.php

@@ -176,7 +176,7 @@ class OAuth
 			'write'          => (stripos($scope, BaseApi::SCOPE_WRITE) !== false),
 			'follow'         => (stripos($scope, BaseApi::SCOPE_FOLLOW) !== false),
 			'push'           => (stripos($scope, BaseApi::SCOPE_PUSH) !== false),
-			'created_at'     => DateTimeFormat::utcNow(DateTimeFormat::MYSQL)];
+			'created_at'     => DateTimeFormat::utcNow()];
 
 		foreach ([BaseApi::SCOPE_READ, BaseApi::SCOPE_WRITE, BaseApi::SCOPE_WRITE, BaseApi::SCOPE_PUSH] as $scope) {
 			if ($fields[$scope] && !$application[$scope]) {

src/Util/DateTimeFormat.php

@@ -52,7 +52,7 @@ class DateTimeFormat
 	 * @return string
 	 * @throws Exception
 	 */
-	public static function utc($time, $format = self::MYSQL)
+	public static function utc(string $time, string $format = self::MYSQL): string
 	{
 		return self::convert($time, 'UTC', 'UTC', $format);
 	}
@@ -102,7 +102,7 @@ class DateTimeFormat
 	 * @return string
 	 * @throws Exception
 	 */
-	public static function utcNow($format = self::MYSQL)
+	public static function utcNow(string $format = self::MYSQL): string
 	{
 		return self::utc('now', $format);
 	}