Squashed commit of the following: (#598)

headless/api/src/main/java/com/tencent/supersonic/headless/api/enums/AggOption.java

@@ -1,5 +1,10 @@
 package com.tencent.supersonic.headless.api.enums;
 
+/**
+ * Aggregation type of metric when query metric without aggregation method
+ * NATIVE: will not use Aggregation
+ * DEFAULT: will use the aggregation method define in the model
+ */
 public enum AggOption {
     NATIVE,
     AGGREGATION,

headless/api/src/main/java/com/tencent/supersonic/headless/api/enums/DatasourceQuery.java

@@ -1,6 +1,10 @@
 package com.tencent.supersonic.headless.api.enums;
 
-
+/**
+ * model datasource define type:
+ * sql_query : view sql begin as select
+ * table_query: dbName.tableName
+ */
 public enum DatasourceQuery {
 
     SQL_QUERY("sql_query"),

headless/api/src/main/java/com/tencent/supersonic/headless/api/enums/ModelSourceType.java

@@ -1,7 +1,12 @@
 package com.tencent.supersonic.headless.api.enums;
 
 import java.util.Objects;
-
+/**
+ * model source table type:
+ * FULL: table without time partition
+ * PARTITION: table with partition field
+ * ZIPPER: table with slowly changing dimension
+ */
 public enum ModelSourceType {
     FULL,
     PARTITION,