API Changes

LoadBalancers can now update addresses for a channel in-place, allowing the channel to re-use existing connections
The previously deprecated affinity API is now deleted. (#3026)

Bug fixes

Overly large messages now return RESOURCE_EXHAUSTED (#2906)
Netty-tcnative load failures may now be detected earlier and cause an exception during build() instead of creating a hung channel (#2599)
OkHttp now ignores unknown SETTINGS (#3032). This resolves an important incompatibility with C-wrapped language instances of gRPC
Fixed dependency specification to avoid wildcards, which are not universally supported (#2961)
Channel.authority() should return the value of overrideAuthority (#2682)

gRPC now does TXT record lookups for implementing service config. Android users will need to add proguard configs to ignore javax.naming.** classes (#2912)
Protobuf bumped to 3.3.0
Disconnect messages have been silenced as non errors (#2960)
Netty has been upgraded to 4.1.11 and Netty TC Native 2.0.1
More work to support HTTP GET method. This work is considered experimental and known to have future incompatible wire changes
Fixed support for the AppEngine development sandbox