Error: Failed to resolve target definition ...: Failed to load p2 metadata repository from location https://download.itemis.com/updates/releases/2.1.1/: Unable to read repository at https://download.itemis.com/updates/releases/2.1.1. ConnectException: ClosedChannelException
Error:
Error: To see the full stack trace of the errors, re-run Maven with the -e switch.
Error: Re-run Maven using the -X switch to enable full debug logging.
Error: Process completed with exit code 1.
need to use https://artifacts.itemis.cloud/repository/p2/xtext-updates/releases/2.1.1/
See also eclipse-xtext/xtext#3646 (comment)