Dependencies

• Update opencensus to 0.11.0 (#3993)

Bug fixes

• bazel: fix protobuf sha256 (#3924)
• core: fix regression in v1.9.0 where the user-agent would be like "grpc-java-netty1.9.0" instead of "grpc-java-netty/1.9.0" (#3974)
• netty: workaround Netty regression in v1.9.0 (netty/netty#7639) which caused TLS failures to fail with "UNAVAILABLE: Channel closed while performing protocol negotiation" instead of useful failure information (#3997, #4030)
• netty: avoid NullPointerException in NettyServerHandler.newStreamException (#3932)
• core: MethodDescriptor.toBuilder() now copies the schemaDescriptor (#3941)
• core: change @Internal and @ExperimentalApi retention policies to CLASS, to enable the upcoming grpc/grpc-java-api-checker to access these annotations (#3994)
• compiler: avoid invoking experimental method in generated code, to clean up the output of the upcoming grpc/grpc-java-api-checker (#4055)

API changes

• core: delete outboundMessage() and inboundMessage() on StreamTracer. (#4014)
• core: deprecate passing ServerCall to StatsTraceContext (#3912)

Features:

• netty: Use Java 9 ALPN if available (#3555). We still want to improve testing with Java 9 ALPN, but it has been reported to work.
• cronet: add build support (#3965)
• bazel: use same version libraries which gradle uses (#3911) (This upgrades Bazel to netty 4.1.17)