@Override
    public String getXmlVersion() {
        return "1.1";
    }
Returns true if the specified character is valid and not a control
character.
This method also checks the surrogate character range from 0x10000 to 0x10FFFF.

@param c The character to check.
stroom-pipeline/src/main/java/stroom/pipeline/reader/Xml11Chars.java