display warning if lock file cannot be deleted, and why

import java.io.FileReader;

import java.io.FileWriter;

import java.io.IOException;

import java.nio.file.Files;

import java.nio.file.Paths;

import java.sql.CallableStatement;

import java.sql.Connection;

import java.sql.DriverManager;

  /* Delete the exonerator-lock file to allow the next executing of this

   * tool. */

  private static void deleteLockFile() {

    new File("exonerator-lock").delete();

    try {

      Files.delete(Paths.get("exonerator-lock"));

    } catch (IOException e) {

      logger.warn("Could not delete lock file \"exonerator-lock\"", e);

    }

  }

}