Fix httpasyncclient-4.x-plugin's memory leak risk (#85)

apm-sniffer/apm-sdk-plugin/httpasyncclient-4.x-plugin/src/main/java/org/apache/skywalking/apm/plugin/httpasyncclient/v4/LeaseRequestCompletedInterceptor.java

@@ -37,6 +37,7 @@ public class LeaseRequestCompletedInterceptor implements InstanceMethodsAroundIn
             conn.getContext().setAttribute(Constants.SKYWALKING_CONTEXT_SNAPSHOT, ContextManager.capture());
             conn.getContext().setAttribute(Constants.SKYWALKING_HTTP_CONTEXT, Constants.HTTP_CONTEXT_LOCAL.get());
         }
+        Constants.HTTP_CONTEXT_LOCAL.remove();
     }
 
     @Override

changes/changes-8.8.0.md

@@ -40,6 +40,7 @@ Release Notes.
 * Add plugin to support okhttp 2.x
 * Optimize okhttp 3.x 4.x plugin to get span time cost precisely
 * Adapt message header properties of RocketMQ 4.9.x
+* Fix httpasyncclient-4.x-plugin's memory leak risk
 
 #### Documentation