private <T> UnaryOperator<T> getStaticValueMapper(final Class<T> clazz) {
        return (UnaryOperator<T>) STATIC_VALUE_MAPPERS.get(clazz);
    }
Intercepts any calls to getConfigObject and allows the returned values to be replaced
with different values for testing.
stroom-app/src/test/java/stroom/test/ConfigMapperSpy.java