public static boolean isS3a(FileSystem fs) {
    try {
      return "s3a".equalsIgnoreCase(fs.getScheme());
    } catch (UnsupportedOperationException ex) {
      return false;
    }
  }
Returns a relative path wrt the parent path.
@param parentPath the parent path.
@param childPath the child path.
@return childPath relative to parent path.
common/src/java/org/apache/hadoop/hive/common/FileUtils.java