Fix otlp log handler reponse error and otlp span convert error (#13468)

Author: weixiang1862

docs/en/changes/changes.md

@@ -91,6 +91,7 @@
 * BanyanDB: fix the `BanyanDBMetricsDAO.multiGet` not work properly in `IndexMode`.
 * BanyanDB: remove `@StoreIDAsTag`, and automatically create a virtual String tag `id` for the SeriesID in `IndexMode`.
 * Remove method `appendMutant` from StorageID.
+* Fix otlp log handler reponse error and otlp span convert error.
 
 #### UI
 

oap-server/server-receiver-plugin/otel-receiver-plugin/src/main/java/org/apache/skywalking/oap/server/receiver/otel/otlp/OpenTelemetryLogHandler.java

@@ -114,9 +114,9 @@ public void export(ExportLogsServiceRequest request, StreamObserver<ExportLogsSe
                         doAnalysisQuietly(service, layer, serviceInstance, logRecord);
                     }
                 });
-            responseObserver.onNext(ExportLogsServiceResponse.getDefaultInstance());
-            responseObserver.onCompleted();
         });
+        responseObserver.onNext(ExportLogsServiceResponse.getDefaultInstance());
+        responseObserver.onCompleted();
     }
 
     private void doAnalysisQuietly(String service, String layer, String serviceInstance, LogRecord logRecord) {

oap-server/server-receiver-plugin/otel-receiver-plugin/src/main/java/org/apache/skywalking/oap/server/receiver/otel/otlp/OpenTelemetryTraceHandler.java

@@ -375,7 +375,7 @@ private String convertToString(AnyValue value) {
             return String.valueOf(value.getIntValue());
         } else if (value.hasKvlistValue()) {
             final JsonObject kvObj = convertToString(value.getKvlistValue().getValuesList());
-            return kvObj.getAsString();
+            return kvObj.toString();
         } else if (value.hasBytesValue()) {
             return new String(Base64.getEncoder().encode(value.getBytesValue().toByteArray()), StandardCharsets.UTF_8);
         }

oap-server/server-receiver-plugin/zipkin-receiver-plugin/src/main/java/org/apache/skywalking/oap/server/receiver/zipkin/trace/SpanForward.java

@@ -79,7 +79,7 @@ public void send(List<Span> spanList) {
             zipkinSpan.setSpanId(span.id());
             zipkinSpan.setParentId(span.parentId());
             zipkinSpan.setName(getNamingControl().formatEndpointName(serviceName, span.name()));
-            zipkinSpan.setDuration(span.duration());
+            zipkinSpan.setDuration(span.duration() == null ? 0 : span.duration());
             if (span.kind() != null) {
                 zipkinSpan.setKind(span.kind().name());
             }