/**
     * Following code implements hibernate 4.3's constraint naming strategy, adapted from: 
     * org.hibernate.mapping.Constraint#generateName(java.lang.String, org.hibernate.mapping.Table, org.hibernate.mapping.Column...)
     */
    @Override
    public Identifier determineForeignKeyName(ImplicitForeignKeyNameSource source) {
        List<String> columnNames = source.getReferencedColumnNames().stream().map(i -> i.getText()).collect(Collectors.toList());
        return generateName("FK_", source.getTableName().getText(), columnNames);
    }

    @Override
    public Identifier determineUniqueKeyName(ImplicitUniqueKeyNameSource source) {
        List<String> columnNames = source.getColumnNames().stream().map(i -> i.getText()).collect(Collectors.toList());
        return generateName("UK_", source.getTableName().getText(), columnNames);
    }

    /**
     * If a constraint is not explicitly named, this is called to generate
     * a unique hash using the table and column names.
     * Static so the name can be generated prior to creating the Constraint.
     * They're cached, keyed by name, in multiple locations.
     */
    private Identifier generateName(String prefix, String table, List<String> columnNames) {

        StringBuilder sb = new StringBuilder( "table`" + table + "`" );

        // Ensure a consistent ordering of columns, regardless of the order
        // they were bound.
        // Clone the list, as sometimes a set of order-dependent Column
        // bindings are given.
        columnNames.sort(String::compareTo);
        for ( String column : columnNames ) {
            String columnName = column == null ? "" : column;
            sb.append("column`").append(columnName).append("`");
        }
        return new Identifier(prefix + hashedName(sb.toString()).toUpperCase(), false);
    }

    /**
     * Hash a constraint name using MD5. Convert the MD5 digest to base 35
     * (full alphanumeric), guaranteeing
     * that the length of the name will always be smaller than the 30
     * character identifier restriction enforced by a few dialects.
     */
    public static String hashedName(String s) {
        try {
            MessageDigest md = MessageDigest.getInstance( "MD5" );
            md.reset();
            md.update( s.getBytes() );
            byte[] digest = md.digest();
            BigInteger bigInt = new BigInteger( 1, digest );
            // By converting to base 35 (full alphanumeric), we guarantee
            // that the length of the name will always be smaller than the 30
            // character identifier restriction enforced by a few dialects.
            return bigInt.toString( 35 );
        }
        catch ( NoSuchAlgorithmException e ) {
            throw new HibernateException( "Unable to generate a hashed Constraint name!", e );
        }
    }