private static void dataVerify(byte[] data, int n, byte v) {
    for (int i = 0; i < n; ++i) {
      assertEquals(v, data[i]);
    }
  }
Verify that all bytes in 'data' have 'v' as value.
hbase-server/src/test/java/org/apache/hadoop/hbase/io/TestFileLink.java