Check user defined variable names

[hclbaur]

Jaxen allows variable names to contain all kinds of characters, which may lead to strange errors when they are referenced. SDT should check for problematic names like "v a r", "var/", "va+r", "%var", etc. Suggestion (easy to implement): user defined variables must be valid SDA node names. Actual naming rules: https://www.w3.org/TR/REC-xml-names/#NT-QName

[hclbaur]

This snippet can be used to check for a valid NCName (chatgpt so beware):

// Regular expression for NCName validation
private static final String NCNAME_REGEX = "^[A-Za-z_][A-Za-z0-9_.-]*$";

public static boolean isValidNCName(String ncName) {
    if (ncName == null || ncName.isEmpty()) {
        return false;
    }
    // Check if the input string matches the NCName pattern
    return ncName.matches(NCNAME_REGEX);
}