public Matcher getMatcher() {
        return matcher;
    }
Throw this when a {@link StackOverflowError} is caught when matching with a regex.
A {@link StackOverflowError} is likely if the regex includes repetitive alternation,
.e.g {@code (A|B)*} with a large input.
<p>
See <a
href="https://stackoverflow.com/questions/7509905/java-lang-stackoverflowerror-while-using-a-regex-to-parse-big-strings">StackOverflow of all places</a>
</p>
stroom-pipeline/src/main/java/stroom/pipeline/xml/converter/ds3/ComplexRegexException.java