Refactor the code and add javadoc

Signed-off-by: Shashwat Sharma <[email protected]>

Author: shshashwat

common/src/main/java/io/pravega/schemaregistry/common/NameUtil.java

@@ -13,7 +13,7 @@
 import com.google.common.base.Strings;
 
 public class NameUtil {
-    private static final String DEFAULT_TYPE = "default_type";
+    private static final String DEFAULT_TYPE = "default_namespace";
     /**
      * Extracts the name from the fully qualified type name. Name represents the last token after ".". 
      * If the qualified name does not contain "." then the name is same as qualified name. 
@@ -63,15 +63,17 @@ public static String qualifiedName(String qualifier, String name) {
 
     /**
      * Type value if the 'type' is not null of empty.
-     * If type is null or empty then the created name is simply 'namespace.groupName'.
+     * If type is null or empty and the namespace is null or empty created name is 'default_namespace.groupName'.
+     * If type is null or empty and namespace is not null or empty then created name is 'namespace.groupName'.
      *
      * @param type the value provided with API call (schemaInfo.getType()).
      * @param groupName the name of the group for schema
      * @param namespace the namespace for the schema
      * @return Provided name or Created name for type in SchemaInfo
      */
     public static String createTypeIfAbsent(String type, String groupName, String namespace) {
-        String nameSpace = Strings.isNullOrEmpty(namespace) ? DEFAULT_TYPE : namespace;
-        return Strings.isNullOrEmpty(type) ? String.format("%s.%s", nameSpace, groupName) : type;
+        Preconditions.checkNotNull(groupName, "Group can not be null");
+        String typeName = Strings.isNullOrEmpty(namespace) ? DEFAULT_TYPE : namespace;
+        return Strings.isNullOrEmpty(type) ? String.format("%s.%s", typeName, groupName) : type;
     }
 }

server/src/main/java/io/pravega/schemaregistry/service/SchemaRegistryService.java

@@ -813,7 +813,6 @@ private boolean checkCompatibility(SchemaInfo schema, GroupProperties groupPrope
     }
 
     private SchemaInfo normalizeSchemaBinary(SchemaInfo schemaInfo, String group, String namespace) {
-        Preconditions.checkNotNull(group, "Group can not be null");
         // validates and the schema binary. 
         ByteBuffer schemaBinary = schemaInfo.getSchemaData();
         boolean isValid = true;

server/src/main/java/io/pravega/schemaregistry/storage/impl/schemas/PravegaKeyValueSchemas.java

@@ -134,7 +134,7 @@ private CompletionStage<String> addNewSchemaRecord(SchemaInfo schemaInfo, Schema
             entries.put(KEY_SERIALIZER.toBytes(new SchemaIdChunkKey(id, i)),
                     new VersionedRecord<>(bytes, null));
         }
-        log.info("Calling update entries for new schema addition");
+        log.trace("Call for update entries for new schema addition with schema {}", schemaInfo);
         return tableStore.updateEntries(SCHEMAS, entries)
                          .thenApply(v -> id);
     }