If you see the following error without SSL:

java.sql.SQLException: [Amazon](500150) Error setting/closing connection: no pg_hba.conf entry for host "x.x.x.x", user "user", database "database", SSL off.

then the following error with SSL enabled:

java.sql.SQLException: [Amazon](500150) Error setting/closing connection: General SSLEngine problem.

You can try appending

sslfactory=org.postgresql.ssl.NonValidatingFactory