protected function getValidationRulesSchemaRequired($validationRules)
	{
		$required = [];

		foreach ($validationRules as $propertyName => $rulesString) {
			$propertyRules = explode('|', $rulesString);

			// Parse property rules to get format/schema
			foreach ($propertyRules as $rule) {
				$explodedRule = explode(':', $rule);
				$ruleName = $explodedRule[0];
				if ($ruleName == 'required') {
					// Check if type is handled
					$schema = $this->getPropertyValidationRulesSchema(
						$propertyRules,
						'Validation rules for property "' . $propertyName . '"'
					);
					if (!is_null($schema->type)) {
						$required[] = $propertyName;
					}
				}
			}
		}

		return count($required) > 0 ? $required : null;
	}