gRPC-Java 1.38.0 released

[Eric Gribkoff]

gRPC Java 1.38.0 is released and is available on Maven Central. https://github.com/grpc/grpc-java/releases/tag/v1.38.0

API Changes

• services: move classes with protobuf dependency into io.grpc.protobuf.services. Users currently using BinaryLogging, HealthChecking, Channelz should migrate to use the corresponding classes in io.grpc.protobuf.services. (#8056)
• ChannelCredentials and ServerCredentials and are now stable. Notably, this also includes TlsChannelCredentials and TlsServerCredentials that allow mTLS configuration without a direct dependency on Netty. The description of the new API can be found in gRFC L74. These APIs are intended to “replace” the implicit security defaults of channels/servers as well as the usePlaintext() and useTransportSecurity() methods on the channel and server builders. The previous APIs are stable so will not be removed. Over time, documentation and examples will be migrated to the new API

Bug Fixes

• xds: Fixed a bug that xDS users may experience null pointer exception in rare cases (#8087)
• netty: Fixed a bug that client RPCs may fail with a wrong exception with message "Maximum active streams violated for this endpoint" when receiving GOAWAY while MAX_CONCURRENT_STREAMS is reached. After the fix the client RPC should fail with UNAVAILABLE status in such a scenario. (#8020)
• xds: Fixed a bug that xDS LB policies may process and propagate load balancing state update from its child LB policy after itself being shut down. This can be cascaded and result in hard-to-reason behaviors if any one layer of the LB policies does not clean up its internal state after shutdown.

Behavior Changes

• core, grpclb, xds: let leaf LB policies explicitly refresh name resolution when subchannel connection is broken. Custom LoadBalancer implementations should refresh name resolution (with Helper.refreshNameResolution()) when seeing its created subchannel becomes IDLE or TRANSIENT_FAILURE. Currently the Channel will do it for you and log a warning. But this operation will be removed in the future releases. (#8048)
• netty: Added support for OpenJSSE

Dependencies

• Upgrade Guava to 30.1 (#8100). As part of #4671 grpc-java will drop support for Java 7, with no impact to Android API levels supported. Guava is going through the same process and in this Guava release it warns when used on Java 7. If you are using Java 7 and are impacted, please comment on #4671. The Java 7 check may be noticed by Android builds and fail without language-level desugaring. We expect most users have already enabled language-level desugaring, but if not it would be necessary to add to your build.gradle:

android {
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
}

• auth: Allow pre- and post-0.25.0 behavior from google-auth-library-java, for Bazel users. google-auth-library-java 0.25.0 changed its behavior for JWT that caused a gRPC test to fail. The failure was benign but prevented Bazel users from using newer versions of the library