On old client versions it was possible to specify that SSL should be used at the connection level options. It is now only possible to specify this as part of the brokerlist sub-options (in addition to much finer-grained control over the keystores/truststores and certificates etc to be used). If you are just using the SSL system properties to define they keystore/truststore etc and have multiple brokers in the brokerlist it is actually more convenient to specify ssl=true at the connection level.
Restoring this will maintain compatibility for drop-in replacement of old clients and also help prevent user confiusion resulting from the URL parsers inability to alert them to the previous ssl configuration going unused.
It will be restored as an ovveride of ssl option in the brokerlist entries.