As B Dalameda noted above, the pitting is a result of moisture settling on the forks when riding in a saline atmosphere such as is found in coastal areas. I found the same problem with my 2012 ST 1300 when I bought it in 2015 from a lobster fisherman who lived on the coast in Nova Scotia, Canada.
The easiest fix is to clean the forks up as best you can (remove what corrosion may exist), then cover them with
3M™ Scotchlite™ Reflective Graphic Film Series 680, black colour. You can get this film from any signmaker, it will cost you no more than $10 to buy what you need to wrap the forks. In daylight, the film appears black, at night when hit by light, it is a brilliant white. The film is available in many different colours, if you want silver (same colour as the OEM paint on the forks), you can get that too. 10 years down the road, if the film is damaged from stones, bug impacts, etc., you just peel it off and replace it.
Michael
3M™ Scotchlite™ Reflective Graphic Film Series 680 on Front Forks