No such extension gson for serialization/org.apache.dubbo.common.serialize.Serialization error

i run ./benchmark.sh dubbo-kryo-server will show error as follow in branch

Exception in thread "main" java.lang.IllegalStateException: No such extension gson for serialization/org.apache.dubbo.common.serialize.Serialization
at org.apache.dubbo.config.utils.ConfigValidationUtils.checkMultiExtension(ConfigValidationUtils.java:680)
at org.apache.dubbo.config.utils.ConfigValidationUtils.checkMultiExtension(ConfigValidationUtils.java:658)
at org.apache.dubbo.config.utils.ConfigValidationUtils.validateProtocolConfig(ConfigValidationUtils.java:574)
at org.apache.dubbo.config.utils.DefaultConfigValidator.validate(DefaultConfigValidator.java:37)
at org.apache.dubbo.config.context.AbstractConfigManager.checkDefaultAndValidateConfigs(AbstractConfigManager.java:588)
at org.apache.dubbo.config.context.ConfigManager.checkConfigs(ConfigManager.java:280)
at org.apache.dubbo.config.context.ConfigManager.loadConfigs(ConfigManager.java:261)
at org.apache.dubbo.config.deploy.DefaultApplicationDeployer.loadApplicationConfigs(DefaultApplicationDeployer.java:243)
at or