@Override
    protected String throwableProxyToString(IThrowableProxy tp) {
        return PATTERN.matcher(super.throwableProxyToString(tp)).replaceAll(PREFIX);
    }
@Test
    void prefixesExceptionsWithExclamationMarks() throws Exception {
        assertThat(converter.throwableProxyToString(proxy))
                .startsWith(String.format("! java.io.IOException: noo%n" +
                                                  "! at io.dropwizard.logging.common.PrefixedThrowableProxyConverterTest.<init>(PrefixedThrowableProxyConverterTest.java:14)%n"));
    }