Simple converter interface designed to be used with stream writer property {@link WstxOutputProperties#P_OUTPUT_INVALID_CHAR_HANDLER}. The idea is that it should be easy to have a way to convert invalid characters such as Ascii control characters into something that is legal to include in XML content. This only allows for simple char-by-char replacements, instead of something more advanced such as escaping. If escaping is needed, check out {@link org.codehaus.stax2.XMLOutputFactory2#P_TEXT_ESCAPER} instead.
Note about exceptions: choice of only allowing throwing of {@link IOException}s is due to the way Woodstox stream writer backend works; XmlWriter
can only throw IOExceptions.