Update references to main branch and update CI
drwxr-xr-x - .github
-rw-r--r-- 85 .gitignore
-rw-r--r-- 1199 CONTRIBUTING.md
-rw-r--r-- 11358 LICENSE
-rw-r--r-- 173 NOTICE
-rw-r--r-- 6157 README.md
drwxr-xr-x - bin
drwxr-xr-x - conf
drwxr-xr-x - contrib
drwxr-xr-x - docs
-rw-r--r-- 13214 pom.xml
drwxr-xr-x - spark
drwxr-xr-x - src