code: public static Path getWriterStagingDir(State state, int numBranches, int branchId, String attemptId) {
      Preconditions.checkArgument(attemptId != null && !attemptId.isEmpty(), "AttemptId cannot be null or empty: " + attemptId);
      return new Path(getWriterStagingDir(state, numBranches, branchId), attemptId);
    }
docs: Get the staging {@link Path} for {@link org.apache.gobblin.writer.DataWriter} that has attemptId in the path.