private static boolean foundAlias(Map<Path, List<String>> pathToAliases, Path path) {
    List<String> aliases = pathToAliases.get(path);
    if ((aliases == null) || (aliases.isEmpty())) {
      return false;
    }
    return true;
  }
Checks if files are in same format as the given input format.

Note: an empty set of files is considered compliant.
ql/src/java/org/apache/hadoop/hive/ql/io/HiveFileFormatUtils.java