CCrmDocument::GetAllowableUserGroups

static function GetAllowableUserGroups($documentType)
{
	$documentType = trim($documentType);
	if ($documentType == '')
		return false;

	$arDocumentID = static::GetDocumentInfo($documentType);
	if ($arDocumentID !== false)
		$documentType = $arDocumentID['TYPE'];

	$arResult = [
		static::GROUP_AUTHOR => GetMessage('CRM_DOCUMENT_AUTHOR'),
		static::GROUP_RESPONSIBLE_HEAD => GetMessage('CRM_DOCUMENT_RESPONSIBLE_HEAD'),
	];

	$arGroupsID = array(1);
	$arUsersID = array();
	$arRelations = CCrmPerms::GetEntityRelations($documentType, BX_CRM_PERM_SELF);
	foreach($arRelations as $relation)
	{
		$preffix = mb_substr($relation, 0, 1);
		if($preffix === 'G')
		{
			$arGroupsID[] = intval(mb_substr($relation, 1));
		}
		elseif($preffix === 'U')
		{
			$arUsersID[] = mb_substr($relation, 1);
		}
	}

	//Crutch for Bitrix24 context (user group management is not supported)
	if(IsModuleInstalled('bitrix24'))
	{
		if (!isset(static::$b24employeeGroupId))
		{
			$siteID = CSite::GetDefSite();
			$dbResult = CGroup::GetList(
				'',
				'',
				[
					'STRING_ID' => 'EMPLOYEES_' . $siteID,
					'STRING_ID_EXACT_MATCH' => 'Y',
				]
			);
			$arEmployeeGroup = $dbResult->fetch();
			static::$b24employeeGroupId = (int) ($arEmployeeGroup['ID'] ?? 0);
		}

		if(!in_array(static::$b24employeeGroupId, $arGroupsID, true))
		{
			$arGroupsID[] = static::$b24employeeGroupId;
		}
	}

	if(!empty($arGroupsID))
	{
		$dbGroupList = CGroup::GetListEx(array('NAME' => 'ASC'), array('ID' => $arGroupsID));
		while ($arGroup = $dbGroupList->Fetch())
		{
			$arResult[$arGroup['ID']] = $arGroup['NAME'];
		}
	}

	if(isset(self::$UNGROUPED_USERS[$documentType]))
	{
		unset(self::$UNGROUPED_USERS[$documentType]);
	}
	self::$UNGROUPED_USERS[$documentType] = $arUsersID;

	if(!empty($arUsersID))
	{
		//Group with empty name will be hidden in group list
		$arResult['ungrouped'] = '';
		//$arResult['ungrouped'] = GetMessage('CRM_DOCUMENT_UNGROUPED_USERS');
	}

	return $arResult;
}