Merge "vpn: Fix NPE in VpnConfig#toString when no ProxyInfo is set" into rvc-dev am: 4cf6815168 am: da7b5b0b09 am: 075cede6fd am: bbbbc3d516 am: 5ed5753d68

Change-Id: I29f4ede7d05b8d6846df67959da5451a17f61805