How to enforce TLS 1.2 protocol (and suppress SSLv3, TLS1 and TLS1.1) for all outbound connections to apigee in the current version ?

[#1]

You can specify the Protocol list as part of the SSLInfo in the target endpoint element For example :- <HTTPTargetConnection><URL>https://foo.com</URL> <SSLInfo><Protocols><Protocol>TLSv1.2</Protocol></Protocols> </SSLInfo></HTTPTargetConnection>

The protocol definition in the <HTTPTargetConnection> will allow only TLS1.2 protocol to work