Description of problem:
When create javamail server on webconsole, Username and Password is required. But in domain/standalone xml, Username and Password are optional. 

Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1. log in webconsole and create a mail server in Configuration->Connector->Mail
2. leave Username and Password empty after fill in other part
3. click Save and see "Invalid input" error for Username and Password

Actual results:
"Invalid input" error was showed when try to save the configuration

Expected results:
no error message should be showed and could save the configuration with empty Username and Passsword

Additional info:
No username and password are allowed in mail subsystem tag in mail subsystem in domain/standalone xml.