Fix checkstyle issues.

Author: passaro

hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/ITestS3APrefetchingInputStream.java

@@ -32,8 +32,6 @@
 import org.apache.hadoop.fs.contract.ContractTestUtils;
 import org.apache.hadoop.fs.s3a.performance.AbstractS3ACostTest;
 import org.apache.hadoop.fs.statistics.IOStatistics;
-import org.apache.hadoop.fs.statistics.StoreStatisticNames;
-import org.apache.hadoop.fs.statistics.StreamStatisticNames;
 
 import static org.apache.hadoop.fs.s3a.Constants.PREFETCH_BLOCK_DEFAULT_SIZE;
 import static org.apache.hadoop.fs.s3a.Constants.PREFETCH_BLOCK_SIZE_KEY;