DialectDerby: Remove unused imports

Change-Id: I719cd9bbe39b21580717089d8276197baeb7ca64

src/main/java/com/google/gwtorm/schema/sql/DialectDerby.java

diff --git a/src/main/java/com/google/gwtorm/schema/sql/DialectDerby.java b/src/main/java/com/google/gwtorm/schema/sql/DialectDerby.java
index d82a791..690ed94 100644
--- a/src/main/java/com/google/gwtorm/schema/sql/DialectDerby.java
+++ b/src/main/java/com/google/gwtorm/schema/sql/DialectDerby.java
@@ -15,10 +15,8 @@
 package com.google.gwtorm.schema.sql;
 
 import com.google.gwtorm.schema.ColumnModel;
-import com.google.gwtorm.schema.SequenceModel;
 import com.google.gwtorm.server.OrmDuplicateKeyException;
 import com.google.gwtorm.server.OrmException;
-import com.google.gwtorm.server.Sequence;
 import com.google.gwtorm.server.StatementExecutor;
 
 import java.sql.Connection;