FIX: NPE when thrift field is nested (#6909)

* FIX: NPE when field is nested

* ADD: change.md
Co-authored-by: NYang Xin <yangxinbj@fenbi.com>

CHANGES.md

@@ -23,6 +23,7 @@ Release Notes.
 * Add an optional agent plugin to support mybatis.
 * Add `spring-cloud-gateway-3.x` optional plugin.
 * Add `okhttp-4.x` plugin.
+* Fix NPE when thrift field is nested in plugin `thrift`
 
 #### OAP-Backend
 * BugFix: filter invalid Envoy access logs whose socket address is empty.

apm-sniffer/apm-sdk-plugin/thrift-plugin/src/main/java/org/apache/skywalking/apm/plugin/thrift/wrapper/ServerInProtocolWrapper.java

@@ -85,7 +85,13 @@ public class ServerInProtocolWrapper extends AbstractProtocolWrapper {
             }
             return readFieldBegin();
         }
-        if (field.type == TType.STOP) {
+
+        return field;
+    }
+
+    @Override
+    public void readMessageEnd() throws TException {
+        super.readMessageEnd();
         Boolean haveCreatedSpan =
                 (Boolean) ContextManager.getRuntimeContext().get(HAVE_CREATED_SPAN);
         if (haveCreatedSpan != null && !haveCreatedSpan) {
@@ -103,8 +109,6 @@ public class ServerInProtocolWrapper extends AbstractProtocolWrapper {
             }
         }
     }
-        return field;
-    }
 
     private ContextCarrier createContextCarrier(Map<String, String> header) {
         ContextCarrier carrier = new ContextCarrier();