RATIS-2393 Add Span Context to RaftRpcRequestProto

[taklwu]

What changes were proposed in this pull request?

We're adding a new map to RaftRpcRequestProto that will be used for upcoming Opentelemetry integration.

see the usage of PoC https://github.com/taklwu/ratis/blob/opentelemetry0129/ratis-common/src/main/java/org/apache/ratis/trace/TraceUtils.java#L235-L251

Another official reference for how this map is going to be inject and extract from the http / rpc header

• https://opentelemetry.io/docs/concepts/context-propagation/
• https://opentelemetry.io/docs/specs/otel/context/api-propagators/#textmap-propagator

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/RATIS-2393

How was this patch tested?

running mvn clean package -DskipTests

(Please explain how this patch was tested. Ex: unit tests, manual tests)
(If this patch involves UI changes, please attach a screen-shot; otherwise, remove this)

[taklwu]

@szetszwo Hi Nicholas, should I directly open PRs to master branch ?

in addition , the test failure doesn't seem to be related to my changes

[INFO] Running org.apache.ratis.netty.TestLeaderElectionWithNetty
OpenJDK 64-Bit Server VM warning: Sharing is only supported for boot loader classes because bootstrap classpath has been appended
Error:  Tests run: 25, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 74.14 s <<< FAILURE! -- in org.apache.ratis.netty.TestLeaderElectionWithNetty
Error:  org.apache.ratis.netty.TestLeaderElectionWithNetty.testChangeListenerToFollower -- Time elapsed: 1.509 s <<< FAILURE!
org.opentest4j.AssertionFailedError: expected: <0> but was: <1>
	at org.apache.ratis.server.impl.LeaderElectionTests.testChangeListenerToFollower(LeaderElectionTests.java:562)
	at java.base/java.lang.reflect.Method.invoke(Method.java:569)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)