with Content
inline fun <T : MessageContent> PossiblySentViaBotCommonMessage<*>.withContent(): PossiblySentViaBotCommonMessage<T>?
inline fun <T : MessageContent> FromChannelGroupContentMessage<*>.withContent(): FromChannelGroupContentMessage<T>?
inline fun <T : MessageContent> AnonymousGroupContentMessage<*>.withContent(): AnonymousGroupContentMessage<T>?
inline fun <T : MessageContent> CommonGroupContentMessage<*>.withContent(): CommonGroupContentMessage<T>?