Remove unused import

Author: winterhazel

plugins/metrics/src/main/java/org/apache/cloudstack/api/ListVolumesUsageHistoryCmd.java

@@ -21,7 +21,6 @@
 
 import org.apache.cloudstack.acl.RoleType;
 import org.apache.cloudstack.api.response.ListResponse;
-import org.apache.cloudstack.api.response.SystemVmResponse;
 import org.apache.cloudstack.api.response.VolumeResponse;
 import org.apache.cloudstack.response.VolumeMetricsStatsResponse;