Add null value to config table

Signed-off-by: NGao Hongtao <hanahmily@gmail.com>

oap-server/server-configuration/configuration-k8s-configmap/src/main/java/org/apache/skywalking/oap/server/configuration/configmap/ConfigmapConfigurationWatcherRegister.java

@@ -19,7 +19,6 @@
 package org.apache.skywalking.oap.server.configuration.configmap;
 
 import io.kubernetes.client.openapi.models.V1ConfigMap;
-import java.util.Objects;
 import java.util.Optional;
 import java.util.Set;
 import lombok.extern.slf4j.Slf4j;
@@ -46,9 +45,7 @@ public class ConfigmapConfigurationWatcherRegister extends ConfigWatcherRegister
             if (log.isDebugEnabled()) {
                 log.debug("read config: name:{} ,value:{}", name, value);
             }
-            if (Objects.nonNull(value)) {
-                configTable.add(new ConfigTable.ConfigItem(name, value));
-            }
+            configTable.add(new ConfigTable.ConfigItem(name, value));
         }
         return Optional.of(configTable);
     }

oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/logging/LoggingConfigWatcher.java

@@ -31,8 +31,8 @@ import org.apache.skywalking.oap.server.core.logging.log4j.OapConfiguration;
 import org.apache.skywalking.oap.server.library.module.ModuleProvider;
 
 /**
- * LoggingConfigWatcher watches the change of logging configuration.
- * Once got the change content, it would apply them to the current logger context.
+ * LoggingConfigWatcher watches the change of logging configuration. Once got the change content, it would apply them to
+ * the current logger context.
  */
 @Slf4j
 public class LoggingConfigWatcher extends ConfigChangeWatcher {
@@ -65,8 +65,10 @@ public class LoggingConfigWatcher extends ConfigChangeWatcher {
         }
         StringBuilder builder = new StringBuilder();
         ctx.getConfiguration().getLoggers().forEach((loggerName, config) -> {
-            builder.append(loggerName).append("-").append(config.getName()).append(":")
-                   .append(config.getLevel()).append(",");
+            builder.append(Strings.isNullOrEmpty(loggerName) ? "Root" : loggerName)
+                   .append(":")
+                   .append(config.getLevel())
+                   .append(",");
         });
         this.content = builder.toString();
     }