Add page about Scala 2 -Xsource:3 to migration guide
#3479
| Job | Run time |
|---|---|
| 4m 20s | |
| 4m 20s |
-Xsource:3 to migration guide
#3479
| Job | Run time |
|---|---|
| 4m 20s | |
| 4m 20s |