Replace reactor's deprecated API (#1885)

Replace deprecated `subscriberContext()` method with either `deferContextual()` or `contextWrite()` methods.

Author: sokomishalov

src/main/java/io/lettuce/core/tracing/BraveTracing.java

@@ -483,7 +483,7 @@ public TraceContext getTraceContext() {
         @Override
         public Mono<TraceContext> getTraceContextLater() {
 
-            return Mono.subscriberContext()
+            return Mono.deferContextual(Mono::justOrEmpty)
                     .filter(it -> it.hasKey(Span.class) || it.hasKey(brave.propagation.TraceContext.class)).map(it -> {
 
                         if (it.hasKey(Span.class)) {

src/main/java/io/lettuce/core/tracing/Tracing.java

@@ -81,7 +81,7 @@ static Tracing disabled() {
      * @return the {@link TraceContextProvider}.
      */
     static Mono<TraceContextProvider> getContext() {
-        return Mono.subscriberContext().filter(c -> c.hasKey(TraceContextProvider.class))
+        return Mono.deferContextual(Mono::justOrEmpty).filter(c -> c.hasKey(TraceContextProvider.class))
                 .map(c -> c.get(TraceContextProvider.class));
     }
 

src/test/java/io/lettuce/core/tracing/BraveTracingIntegrationTests.java

@@ -178,7 +178,7 @@ void reactivePingWithTrace() {
 
         StatefulRedisConnection<String, String> connect = client.connect();
         connect.reactive().ping() //
-                .subscriberContext(it -> it.put(TraceContext.class, trace.context())) //
+                .contextWrite(it -> it.put(TraceContext.class, trace.context())) //
                 .as(StepVerifier::create) //
                 .expectNext("PONG").verifyComplete();
 
@@ -200,7 +200,7 @@ void reactiveGetAndSetWithTrace() {
         StatefulRedisConnection<String, String> connect = client.connect();
         connect.reactive().set("foo", "bar") //
                 .then(connect.reactive().get("foo")) //
-                .subscriberContext(it -> it.put(TraceContext.class, trace.context())) //
+                .contextWrite(it -> it.put(TraceContext.class, trace.context())) //
                 .as(StepVerifier::create) //
                 .expectNext("bar").verifyComplete();
 
@@ -224,8 +224,7 @@ void reactiveGetAndSetWithTraceProvider() {
 
         StatefulRedisConnection<String, String> connect = client.connect();
         connect.reactive().set("foo", "bar").then(connect.reactive().get("foo"))
-                .subscriberContext(io.lettuce.core.tracing.Tracing
-                        .withTraceContextProvider(() -> BraveTracing.BraveTraceContext.create(trace.context()))) //
+                .contextWrite(io.lettuce.core.tracing.Tracing.withTraceContextProvider(() -> BraveTracing.BraveTraceContext.create(trace.context()))) //
                 .as(StepVerifier::create) //
                 .expectNext("bar").verifyComplete();