public Collection<String> getAllowedParameters() throws GuacamoleException {
        return environment.getPropertyCollection(QUICKCONNECT_ALLOWED_PARAMETERS);
    }
Return the list of allowed parameters to be set by connections created
using the QuickConnect module, or null if none are defined (thereby
allowing all parameters to be set).

@return 
   The list of allowed parameters to be set by connections crated using
   the QuickConnect module.

@throws GuacamoleException
   If guacamole.properties cannot be parsed.
extensions/guacamole-auth-quickconnect/src/main/java/org/apache/guacamole/auth/quickconnect/conf/ConfigurationService.java