Remove redundant null checks in rxjava2 instrumentation (current Context is never null)

Author: mcculls

dd-java-agent/instrumentation/rxjava/rxjava-2.0/src/main/java/datadog/trace/instrumentation/rxjava2/CompletableInstrumentation.java

@@ -39,7 +39,7 @@ public static class CaptureParentSpanAdvice {
     @Advice.OnMethodExit(suppress = Throwable.class)
     public static void onConstruct(@Advice.This final Completable completable) {
       Context parentContext = currentContext();
-      if (parentContext != null && parentContext != rootContext()) {
+      if (parentContext != rootContext()) {
         InstrumentationContext.get(Completable.class, Context.class)
             .put(completable, parentContext);
       }

dd-java-agent/instrumentation/rxjava/rxjava-2.0/src/main/java/datadog/trace/instrumentation/rxjava2/FlowableInstrumentation.java

@@ -39,7 +39,7 @@ public static class CaptureParentSpanAdvice {
     @Advice.OnMethodExit(suppress = Throwable.class)
     public static void onConstruct(@Advice.This final Flowable<?> flowable) {
       Context parentContext = currentContext();
-      if (parentContext != null && parentContext != rootContext()) {
+      if (parentContext != rootContext()) {
         InstrumentationContext.get(Flowable.class, Context.class).put(flowable, parentContext);
       }
     }

dd-java-agent/instrumentation/rxjava/rxjava-2.0/src/main/java/datadog/trace/instrumentation/rxjava2/MaybeInstrumentation.java

@@ -38,7 +38,7 @@ public static class CaptureParentSpanAdvice {
     @Advice.OnMethodExit(suppress = Throwable.class)
     public static void onConstruct(@Advice.This final Maybe<?> maybe) {
       Context parentContext = currentContext();
-      if (parentContext != null && parentContext != rootContext()) {
+      if (parentContext != rootContext()) {
         InstrumentationContext.get(Maybe.class, Context.class).put(maybe, parentContext);
       }
     }

dd-java-agent/instrumentation/rxjava/rxjava-2.0/src/main/java/datadog/trace/instrumentation/rxjava2/ObservableInstrumentation.java

@@ -38,7 +38,7 @@ public static class CaptureParentSpanAdvice {
     @Advice.OnMethodExit(suppress = Throwable.class)
     public static void onConstruct(@Advice.This final Observable<?> observable) {
       Context parentContext = currentContext();
-      if (parentContext != null) {
+      if (parentContext != rootContext()) {
         InstrumentationContext.get(Observable.class, Context.class).put(observable, parentContext);
       }
     }
@@ -52,7 +52,7 @@ public static ContextScope onSubscribe(
       if (observer != null) {
         Context parentContext =
             InstrumentationContext.get(Observable.class, Context.class).get(observable);
-        if (parentContext != null && parentContext != rootContext()) {
+        if (parentContext != null) {
           // wrap the observer so spans from its events treat the captured span as their parent
           observer = new TracingObserver<>(observer, parentContext);
           // attach the context here in case additional observers are created during subscribe

dd-java-agent/instrumentation/rxjava/rxjava-2.0/src/main/java/datadog/trace/instrumentation/rxjava2/SingleInstrumentation.java

@@ -39,7 +39,7 @@ public static class CaptureParentSpanAdvice {
     @Advice.OnMethodExit(suppress = Throwable.class)
     public static void onConstruct(@Advice.This final Single<?> single) {
       Context parentContext = currentContext();
-      if (parentContext != null) {
+      if (parentContext != rootContext()) {
         InstrumentationContext.get(Single.class, Context.class).put(single, parentContext);
       }
     }
@@ -52,7 +52,7 @@ public static ContextScope onSubscribe(
         @Advice.Argument(value = 0, readOnly = false) SingleObserver<?> observer) {
       if (observer != null) {
         Context parentContext = InstrumentationContext.get(Single.class, Context.class).get(single);
-        if (parentContext != null && parentContext != rootContext()) {
+        if (parentContext != null) {
           // wrap the observer so spans from its events treat the captured span as their parent
           observer = new TracingSingleObserver<>(observer, parentContext);
           // attach the context here in case additional observers are created during subscribe