@Test
    public void testSomeMissingHeaders() throws Exception {
        Metadata metadata = new Metadata();
        InputStream stream = getStream("test-documents/testRFC822-limitedheaders");
        ContentHandler handler = new BodyContentHandler();
        ParseContext context = new ParseContext();
        context.set(Parser.class, EXTRACT_ALL_ALTERNATIVES_PARSER);

        EXTRACT_ALL_ALTERNATIVES_PARSER.parse(stream, handler, metadata, context);
        assertEquals(true, metadata.isMultiValued(TikaCoreProperties.CREATOR));
        assertEquals("xyz", metadata.getValues(TikaCoreProperties.CREATOR)[0]);
        assertEquals("abc", metadata.getValues(TikaCoreProperties.CREATOR)[1]);
        assertEquals(true, metadata.isMultiValued(Metadata.MESSAGE_FROM));
        assertEquals("xyz", metadata.getValues(Metadata.MESSAGE_FROM)[0]);
        assertEquals("abc", metadata.getValues(Metadata.MESSAGE_FROM)[1]);
        assertEquals(true, metadata.isMultiValued(Metadata.MESSAGE_TO));
        assertEquals("abc", metadata.getValues(Metadata.MESSAGE_TO)[0]);
        assertEquals("def", metadata.getValues(Metadata.MESSAGE_TO)[1]);
        assertEquals("abcd", metadata.get(TikaCoreProperties.TITLE));
        assertEquals("abcd", metadata.get(TikaCoreProperties.SUBJECT));
        assertContains("bar biz bat", handler.toString());
    }
Test for TIKA-678 - not all headers may be present
tika-parsers/tika-parsers-standard/tika-parsers-standard-modules/tika-parser-mail-module/src/test/java/org/apache/tika/parser/mail/RFC822ParserTest.java