Merge two columns in Power Query (M)

Hi all,

Anyone knows howto merge two columns in Power Query with space as delimiter but not on the blank values?
Ex:

Column1    Column2  Merge

A                 A             A A (space between)

B                 B              B B (space between)

C                                 C (without space at the end)

D                                 D (without space at the end)

E                 E               E E (space between)

I',m going to do this on Street name, street number and street letter. There is a lot of addresses without street letter, but I dont want to have the space at end on the street name + street number without street letter in the tables (null)

Regards
Marius