change the import statements in SessionWindowProcessor class
@@ -45,8 +45,12 @@ import org.wso2.siddhi.query.api.definition.Attribute;
import org.wso2.siddhi.query.api.exception.SiddhiAppValidationException;
import org.wso2.siddhi.query.api.expression.Expression;
-import java.util.*;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
+import java.util.LinkedHashMap;
import static java.util.stream.Collectors.toMap;
