Add comment for UpsertAssembler

Author: momosetkn

doma-core/src/main/java/org/seasar/doma/jdbc/dialect/Db2UpsertAssembler.java

@@ -12,6 +12,7 @@
 import org.seasar.doma.jdbc.query.UpsertAssemblerSupport;
 import org.seasar.doma.jdbc.query.UpsertSetValue;
 
+// Same as OracleUpsertAssembler
 public class Db2UpsertAssembler implements UpsertAssembler {
   private final PreparedSqlBuilder buf;
   private final EntityType<?> entityType;

doma-core/src/main/java/org/seasar/doma/jdbc/dialect/HsqldbUpsertAssembler.java

@@ -12,6 +12,7 @@
 import org.seasar.doma.jdbc.query.UpsertAssemblerSupport;
 import org.seasar.doma.jdbc.query.UpsertSetValue;
 
+// Same as MsSqlUpsertAssembler
 public class HsqldbUpsertAssembler implements UpsertAssembler {
   private final PreparedSqlBuilder buf;
   private final EntityType<?> entityType;

doma-core/src/main/java/org/seasar/doma/jdbc/dialect/SqliteUpsertAssembler.java

@@ -12,6 +12,7 @@
 import org.seasar.doma.jdbc.query.UpsertAssemblerSupport;
 import org.seasar.doma.jdbc.query.UpsertSetValue;
 
+// Same as PostgreSqlUpsertAssembler
 public class SqliteUpsertAssembler implements UpsertAssembler {
   private final PreparedSqlBuilder buf;
   private final EntityType<?> entityType;