private boolean isSpecifierMapValid(String type, String key, Object value)
            throws SAXException {
        if (key.isEmpty()) {
            err("A specifier map defined in a \u201c" + type + "\u201d"
                    + " property within the content of a \u201cscript\u201d"
                    + " element with a \u201ctype\u201d attribute whose value"
                    + " is \u201cimportmap\u201d must only contain non-empty"
                    + " keys.");
            return false;
        }
        if (!(value instanceof String)) {
            err("A specifier map defined in a \u201c" + type + "\u201d"
                    + " property within the content of a \u201cscript\u201d"
                    + " element with a \u201ctype\u201d attribute whose value"
                    + " is \u201cimportmap\u201d must only contain string"
                    + " values.");
            return false;
        }
        String sValue = (String) value;
        if (!isValidURL(sValue)) {
            err("A specifier map defined in a \u201c" + type + "\u201d"
                    + " property within the content of a \u201cscript\u201d"
                    + " element with a \u201ctype\u201d attribute whose value"
                    + " is \u201cimportmap\u201d must only contain valid URL"
                    + " values.");
            return false;
        }
        if (key.endsWith("/") && !sValue.endsWith("/")) {
            err("A specifier map defined in a \u201c" + type + "\u201d"
                    + " property within the content of a \u201cscript\u201d"
                    + " element with a \u201ctype\u201d attribute whose value"
                    + " is \u201cimportmap\u201d must have values that end with"
                    + " \u201c/\u201d when its corresponding key ends with"
                    + " \u201c/\u201d.");
            return false;
        }
        return true;
    }
@see nu.validator.checker.Checker#endElement(java.lang.String,
     java.lang.String, java.lang.String)
src/nu/validator/checker/schematronequiv/Assertions.java