Fix missing language field. (#2174)

oap-server/server-storage-plugin/storage-elasticsearch-plugin/src/main/java/org/apache/skywalking/oap/server/storage/plugin/elasticsearch/query/MetadataQueryEsDAO.java

@@ -197,6 +197,8 @@ public class MetadataQueryEsDAO extends EsDAO implements IMetadataQueryDAO {
                 JsonObject properties = GSON.fromJson(propertiesString, JsonObject.class);
                 if (properties.has(LANGUAGE)) {
                     serviceInstance.setLanguage(LanguageTrans.INSTANCE.value(properties.get(LANGUAGE).getAsString()));
+                } else {
+                    serviceInstance.setLanguage(Language.UNKNOWN);
                 }
 
                 if (properties.has(OS_NAME)) {

oap-server/server-storage-plugin/storage-jdbc-hikaricp-plugin/src/main/java/org/apache/skywalking/oap/server/storage/plugin/jdbc/h2/dao/H2MetadataQueryDAO.java

@@ -222,6 +222,8 @@ public class H2MetadataQueryDAO implements IMetadataQueryDAO {
                         JsonObject properties = GSON.fromJson(propertiesString, JsonObject.class);
                         if (properties.has(LANGUAGE)) {
                             serviceInstance.setLanguage(LanguageTrans.INSTANCE.value(properties.get(LANGUAGE).getAsString()));
+                        } else {
+                            serviceInstance.setLanguage(Language.UNKNOWN);
                         }
 
                         if (properties.has(OS_NAME)) {