[SYSTEMDS-3876] cleanup

Author: exolightor

src/test/java/org/apache/sysds/test/component/matrix/MatrixMultiplyTest.java

@@ -25,7 +25,6 @@
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
-import java.lang.String;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;