update string buffer to string builder.

Author: liuhongyuand

EasyRest/src/main/java/tech/dbgsoftware/easyrest/model/request/Request.java

@@ -50,6 +50,8 @@ public Request(FullHttpRequest fullHttpRequest) {
                     }
                 }));
             }
+        } catch (Exception e) {
+            LogUtils.error("Ref count = " + fullHttpRequest.refCnt() + " " + e.getMessage());
         } finally {
             fullHttpRequest.release();
         }

EasyRest/src/main/java/tech/dbgsoftware/easyrest/network/NettyInit.java

@@ -243,15 +243,18 @@ private void registerUserHandlers(ChannelPipeline pipeline){
             userHandlers.forEach((name, handler) -> {
                 Function<Map<String, Boolean>, ChannelHandler> handlerPredicate = newHandler -> {
                     try {
-                        if (!newHandler.get(name)) {
+                        if (newHandler != null && handler != null && !newHandler.get(name)) {
                             return handler.getClass().newInstance();
                         }
                     } catch (InstantiationException | IllegalAccessException e) {
                         LOGGER.error(e.getMessage(), e);
                     }
                     return handler;
                 };
-                pipeline.addLast(workerEventLoopGroup, handlerPredicate.apply(isSharableMapping));
+                ChannelHandler channelHandler = handlerPredicate.apply(isSharableMapping);
+                if (channelHandler != null) {
+                    pipeline.addLast(workerEventLoopGroup, channelHandler);
+                }
             });
         }
     }