SymphonyClientConfigBuilder doesn't correctly handle null configuration values

[pmonks]

org.symphonyoss.client.SymphonyClientConfigBuilder has a bug related to null handling, ultimately caused by the unfortunate fact that java.util.Properties does not allow null values to be stored (though it will happily return them, when they're populated via other means 🤦‍♂️).

Neither org.symphonyoss.client.SymphonyClientConfigBuilder nor org.symphonyoss.client.SymphonyClientConfig protect against this themselves.

[pmonks]

This was fixed in rev 81680eb.