Incompatibilities in Ambari and CDAP Ambari Service

Ambari introduced the "empty-value-valid" tag support into Ambari 2.2, so versions of Ambari prior to this do not allow empty values in any properties listed in a configuration dictionary. This means that all properties must have values. This forces the user to input "dummy" values into the unused fields.

This can cause confusion for the user and makes it difficult to assemble a working CDAP configuration.

This should be added to the Release Notes/Known Issues for CDAP 3.5+ and we should set the CDAP Ambari Service to conflict with ambari-server < 2.2 to prevent this from affecting additional users.