### Question:
ContentNegotiator { public ContentNegotiator support(final MediaType mediaType) { if(mediaType!=null) { this.mediaTypes.add(mediaType); } return this; } private  ContentNegotiator(); Variant onError(); ContentNegotiator onError(final Variant variant); ContentNegotiator support(final MediaType mediaType); ContentNegotiator support(final CharacterEncoding characterEncoding); ContentNegotiator support(final Language language); ContentNegotiator support(final Alternative alternative); ContentNegotiator accept(final String header); ContentNegotiator acceptCharset(final String header); ContentNegotiator acceptLanguage(final String header); NegotiationResult negotiate(); static ContentNegotiator newInstance();  }### Answer:
@Test public void ignoresNullAsSupportedMediaTypes() throws Exception { checkCannotNegotiate( specRequirementsNegotiator(). support((MediaType)null)); }
@Test public void ignoresNullAsSupportedCharacterEncoding() throws Exception { checkCannotNegotiate( specRequirementsNegotiator(). support((CharacterEncoding)null)); }
@Test public void ignoresNullAsSupportedLanguage() throws Exception { checkCannotNegotiate( specRequirementsNegotiator(). support((Language)null)); }
@Test public void ignoresNullAsSupportedAlternative() throws Exception { checkCannotNegotiate( specRequirementsNegotiator(). support((Alternative)null)); }