### Question:
DMNDIExtensionsRegister implements DMNExtensionRegister { @Override public void registerExtensionConverters(final XStream xStream) { xStream.processAnnotations(ComponentsWidthsExtension.class); xStream.processAnnotations(ComponentWidths.class); xStream.processAnnotations(ExternalLink.class); xStream.alias(COMPONENT_WIDTH_ALIAS, Double.class); xStream.alias(EXTERNAL_LINK_ALIAS, ExternalLink.class); xStream.registerConverter(new ExternalLinksConverter(xStream)); xStream.registerConverter(new ComponentWidthsConverter(xStream)); }  @Override void registerExtensionConverters(final XStream xStream); @Override void beforeMarshal(final Object o,
                              final QNameMap qmap);  }### Answer:
@Test public void testRegisterExtensionConverters() { register.registerExtensionConverters(xStream); verify(xStream).processAnnotations(eq(ComponentsWidthsExtension.class)); verify(xStream).processAnnotations(eq(ComponentWidths.class)); verify(xStream).processAnnotations(eq(ExternalLink.class)); verify(xStream).alias(eq(COMPONENT_WIDTH_ALIAS), eq(Double.class)); verify(xStream, times(2)).registerConverter(converterCaptor.capture()); verify(xStream).alias(eq(EXTERNAL_LINK_ALIAS), eq(ExternalLink.class)); final List<Converter> values = converterCaptor.getAllValues(); assertThat(values).hasAtLeastOneElementOfType(ComponentWidthsConverter.class); assertThat(values).hasAtLeastOneElementOfType(ExternalLinksConverter.class); }