[#4035] fix invocation context loss issue (#4087)

Author: yanghao605

handlers/handler-tracing-zipkin/src/main/java/org/apache/servicecomb/tracing/zipkin/ZipkinTracingFilter.java

@@ -37,21 +37,14 @@
 public class ZipkinTracingFilter extends AbstractFilter implements ConsumerFilter, ProviderFilter {
   public static final String NAME = "zipkin";
 
-  private ZipkinConsumerDelegate consumer;
-
-  private ZipkinProviderDelegate producer;
+  @Autowired
+  private HttpTracing httpTracing;
 
   @Override
   public String getName() {
     return NAME;
   }
 
-  @Autowired
-  public void setHttpTracing(HttpTracing httpTracing) {
-    this.consumer = new ZipkinConsumerDelegate(httpTracing);
-    this.producer = new ZipkinProviderDelegate(httpTracing);
-  }
-
   @SuppressWarnings({"try", "unused"})
   @Override
   public CompletableFuture<Response> onFilter(Invocation invocation, FilterNode nextNode) {
@@ -66,9 +59,9 @@ public CompletableFuture<Response> onFilter(Invocation invocation, FilterNode ne
 
   private ZipkinTracingDelegate collectTracing(Invocation invocation) {
     if (PROVIDER.equals(invocation.getInvocationType())) {
-      return producer;
+      return new ZipkinProviderDelegate(httpTracing);
     }
 
-    return consumer;
+    return new ZipkinConsumerDelegate(httpTracing);
   }
 }