question: public DbSchemaChanger beginChange ( ) throws Exception { backupFile = File . createTempFile ( "dataobj" , ".class" ) ; log . info ( "copy from {} to {}" , classFile . getAbsolutePath ( ) , backupFile . getAbsolutePath ( ) ) ; copyFile ( classFile , backupFile ) ; cc . defrost ( ) ; return this ; }
target:  Begin change the schema This method should be called before making any changes to the class