HSQLDB never closes DB connection

I'm playing with this kind of database, and I've tried to close the HSQLDB connection after I used it, but it's still opened at the end.

Code:

//----This methods are in a specific connection class file
    public static Connection conn = null;
    public static Connection getConnection(){       
        try {
            input = new FileInputStream("PathToMyPropertiesFile");
            prop.load(input);
            //The properties constants are correctly checked
            Class.forName(prop.getProperty("DRIVER_HSQLDB"));
            conn = DriverManager.getConnection(prop.getProperty("CONN_HSQLDB"));
        }
        catch(ClassNotFoundException | SQLException e) {
            LOG.log(null,"Error: "+e);
        }
        catch (IOException ex) {
            LOG.log(null,"FILE ERROR: "+ex);
        }
        finally {
            if (input != null) {
                try {
                    input.close();
                } catch (Exception e) {
                    LOG.log(null,"CLOSE ERROR: "+e);
                }
            }
        }   
        return conn;
    }
public static boolean stopConn() {
        try {
            if(conn != null) {
                conn.close();
                System.err.println("\nCLOSE CONN\n"+conn);
                return true;
            }
        } 
        catch (SQLException e) {
            e.printStackTrace();
            return false;
        }
        return false;
    }

//========= the other class file with the methods to use the conneciton
public static boolean insertUser(String uName, String uEmail){
        Connection con;
        con = ConnectionDB.getConnection();
        PreparedStatement ps = null;
        try {
            String consulta = "insert into USERS (\"NICK\",\"EMAIL\") VALUES(?,?);";
            ps = con.prepareStatement(consulta);

            System.err.println(ps);
            ps.setString(1,uName);
            ps.setString(2,uEmail);
            System.err.println("\nASSIGNATION\n"+ps);

            if(ps.executeUpdate() == 1) {
                System.err.println("\nTRUE\n");
                return true;
            }
        }
        catch(SQLException e) {
            e.printStackTrace();
        }
        finally {
            try {
                System.err.println("\nFINALLY\n"+ps);
                if(ps != null) {
                    ps.close();
                    System.err.println("\nCLOSE PS\n"+ps);
                }
                if(con != null) {
                    con.close();
                    System.err.println("\nCLOSE CON\n"+con);
                    if(ConnectionDB.stopConn()) {
                        System.err.println("\nALL IS OK\n"+ConnectionDB.conn);
                    }
                    else {
                        System.err.println("\nMEEEEKKKK!!!\n"+ConnectionDB.conn);
                    }   
                }
            }
        }
        return false;
    }

The console give me this results, and I don't know why never the connection is closed because I tried to close it twice. If someone has an idea please tell me.

org.hsqldb.jdbc.JDBCPreparedStatement@4501280b[sql=[insert into USERS ("NICK","EMAIL") VALUES(?,?);], parameters=[[null], [null]]]

ASSIGNATION org.hsqThis is my cldb.jdbc.JDBCPreparedStatement@4501280b[sql=[insert into USERS ("NICK","EMAIL") VALUES(?,?);], parameters=[[extra], [extra@mail.com]]]

TRUE

FINALLY org.hsqldb.jdbc.JDBCPreparedStatement@4501280b[sql=[insert into USERS ("NICK","EMAIL") VALUES(?,?);], parameters=[[extra], [extra@mail.com]]]

CLOSE PS org.hsqldb.jdbc.JDBCPreparedStatement@4501280b[closed]

CLOSE CON org.hsqldb.jdbc.JDBCConnection@3e5b87f5

CLOSE CONN org.hsqldb.jdbc.JDBCConnection@3e5b87f5

ALL IS OK org.hsqldb.jdbc.JDBCConnection@3e5b87f5

Closing a JDBC connections does not close an in-process database. This allows you to open and close different connections during the runtime of your application.

You need to execute a JDBC Statement to shutdown the database. The SQL statement to execute is "SHUTDOWN".

It is possible to add a connection property "shutdown=true" to the JDBC connection URL to force a quick shutdown when the last connection to the in-process database is closed. But this is mainly useful for readonly or test databases. A full SHUTDOWN allows the database to open quickly the next time a connection is made.

See the Guide http://hsqldb.org/doc/2.0/guide/running-chapt.html#rgc_inprocess