Bug of CubeMX 5.1. 0 with Hardware Flow Control (RS485)

I try made project with RS485

After open project I have

uart_de\uart_de.axf: Error: L6218E: Undefined symbol HAL_RS485Ex_Init (referred from main.o).

Resolve problem - add to project file

sm32f7xx_hal_uart_ex.c

After this all is OK