### Question:
MSEmailHeaderConverter { public MSEmailHeader convertToMSEmailHeader(Envelope envelope) { Preconditions.checkNotNull(envelope); return MSEmailHeader.builder() .from(toMSAddresses(envelope.getFrom())) .replyTo(toMSAddresses(envelope.getReplyTo())) .to(toMSAddresses(envelope.getTo())) .cc(toMSAddresses(envelope.getCc())) .subject(envelope.getSubject()) .date(envelope.getDate()) .build(); } @Inject @VisibleForTesting  MSEmailHeaderConverter(UserEmailParserUtils emailParserUtils); MSEmailHeader convertToMSEmailHeader(Envelope envelope);  }### Answer:
@Test(expected=NullPointerException.class) public void testMSEmailHeaderConverterNullPointer() { msEmailHeaderConverter.convertToMSEmailHeader(null); }