retain propagator context for random trace-ids

Author: cleverchuk

sdk/trace/src/main/java/io/opentelemetry/sdk/trace/SdkSpanBuilder.java

@@ -36,11 +36,6 @@
 
 /** {@link SdkSpanBuilder} is SDK implementation of {@link SpanBuilder}. */
 class SdkSpanBuilder implements SpanBuilder {
-
-  private static final Context ROOT_CONTEXT_WITH_RANDOM_TRACE_ID_BIT =
-      preparePrimordialContext(
-          TraceFlags.builder().setRandomTraceId(true).build(), TraceState.getDefault());
-
   private final String spanName;
   private final InstrumentationScopeInfo instrumentationScopeInfo;
   private final TracerSharedState tracerSharedState;
@@ -198,7 +193,11 @@ public Span startSpan() {
       if (idGenerator.generatesRandomTraceIds()) {
         isTraceIdRandom = true;
         // Replace parentContext for sampling with one with RANDOM_TRACE_ID bit set
-        parentContextForSampler = ROOT_CONTEXT_WITH_RANDOM_TRACE_ID_BIT;
+        SpanContext primordialSpan = SpanContext.create(
+                TraceId.getInvalid(), SpanId.getInvalid(),
+                TraceFlags.builder().setRandomTraceId(true).build(),
+                TraceState.getDefault());
+        parentContextForSampler = parentContext.with(Span.wrap(primordialSpan));
       } else {
         isTraceIdRandom = false;
       }