linkedChatId property
Optional. Unique identifier for the linked chat, i.e. the discussion group identifier for a channel and vice versa; for supergroups and channel chats. This identifier may be greater than 32 bits and some programming languages may have difficulty/silent defects in interpreting it. But it is smaller than 52 bits, so a signed 64 bit integer or double-precision float type are safe for storing this identifier. Returned only in getChat.
Implementation
int? linkedChatId;