Move webflux context injection to the decorator (#686)

* move webflux context injection to the decorator

* add if statement

instrumentation-core/spring/spring-webflux-5.0/src/main/java/io/opentelemetry/instrumentation/springwebflux/client/SpringWebfluxHttpClientDecorator.java

@@ -16,19 +16,24 @@
 
 package io.opentelemetry.instrumentation.springwebflux.client;
 
-import io.opentelemetry.OpenTelemetry;
+import static io.opentelemetry.OpenTelemetry.getPropagators;
+import static io.opentelemetry.OpenTelemetry.getTracerProvider;
+import static io.opentelemetry.instrumentation.springwebflux.client.HttpHeadersInjectAdapter.SETTER;
+
+import io.grpc.Context;
 import io.opentelemetry.auto.bootstrap.instrumentation.decorator.HttpClientDecorator;
 import io.opentelemetry.trace.Span;
 import io.opentelemetry.trace.Tracer;
 import java.net.URI;
 import java.util.List;
+import org.springframework.http.HttpHeaders;
 import org.springframework.web.reactive.function.client.ClientRequest;
 import org.springframework.web.reactive.function.client.ClientResponse;
 
 class SpringWebfluxHttpClientDecorator extends HttpClientDecorator<ClientRequest, ClientResponse> {
 
   public static final Tracer TRACER =
-      OpenTelemetry.getTracerProvider().get("io.opentelemetry.auto.spring-webflux-5.0");
+      getTracerProvider().get("io.opentelemetry.auto.spring-webflux-5.0");
   public static final SpringWebfluxHttpClientDecorator DECORATE =
       new SpringWebfluxHttpClientDecorator();
 
@@ -37,6 +42,10 @@ class SpringWebfluxHttpClientDecorator extends HttpClientDecorator<ClientRequest
     span.setAttribute("message", "The subscription was cancelled");
   }
 
+  public void inject(Context context, HttpHeaders httpHeaders) {
+    getPropagators().getHttpTextFormat().inject(context, httpHeaders, SETTER);
+  }
+
   @Override
   protected String method(final ClientRequest httpRequest) {
     return httpRequest.method().name();

instrumentation-core/spring/spring-webflux-5.0/src/main/java/io/opentelemetry/instrumentation/springwebflux/client/WebClientTracingFilter.java

@@ -16,13 +16,10 @@
 
 package io.opentelemetry.instrumentation.springwebflux.client;
 
-import static io.opentelemetry.instrumentation.springwebflux.client.HttpHeadersInjectAdapter.SETTER;
 import static io.opentelemetry.instrumentation.springwebflux.client.SpringWebfluxHttpClientDecorator.DECORATE;
 import static io.opentelemetry.instrumentation.springwebflux.client.SpringWebfluxHttpClientDecorator.TRACER;
-import static io.opentelemetry.trace.Span.Kind.CLIENT;
 
 import io.grpc.Context;
-import io.opentelemetry.OpenTelemetry;
 import io.opentelemetry.context.Scope;
 import io.opentelemetry.trace.Span;
 import io.opentelemetry.trace.Tracer;
@@ -52,18 +49,13 @@ public class WebClientTracingFilter implements ExchangeFilterFunction {
 
   @Override
   public Mono<ClientResponse> filter(final ClientRequest request, final ExchangeFunction next) {
-    final Span span =
+    final Span span = DECORATE.getOrCreateSpan(request, tracer);
-        tracer.spanBuilder(DECORATE.spanNameForRequest(request)).setSpanKind(CLIENT).startSpan();
     DECORATE.afterStart(span);
 
     try (final Scope scope = TRACER.withSpan(span)) {
       final ClientRequest mutatedRequest =
           ClientRequest.from(request)
-              .headers(
+              .headers(httpHeaders -> DECORATE.inject(Context.current(), httpHeaders))
-                  httpHeaders ->
-                      OpenTelemetry.getPropagators()
-                          .getHttpTextFormat()
-                          .inject(Context.current(), httpHeaders, SETTER))
               .build();
       DECORATE.onRequest(span, mutatedRequest);