### Question:
NeoInserter implements AutoCloseable { public static String clean(String x) { if (Strings.isNullOrEmpty(x) || NULL_PATTERN.matcher(x).find()) { return null; } return Strings.emptyToNull(CharMatcher.JAVA_ISO_CONTROL.trimAndCollapseFrom(x, ' ').trim()); } private  NeoInserter(UsageDao dao, File storeDir, int batchSize, @Nullable Meter insertMeter); static NeoInserter create(UsageDao dao, File storeDir, int batchSize, @Nullable MetricRegistry registry); InsertMetadata insert(File dwca, Map<String, UUID> constituents); static String clean(String x); @Override void close();  }### Answer:
@Test public void testClean() throws Exception { assertNull(NeoInserter.clean(null)); assertNull(NeoInserter.clean(" ")); assertNull(NeoInserter.clean(" ")); assertNull(NeoInserter.clean("\\N")); assertNull(NeoInserter.clean("NULL")); assertNull(NeoInserter.clean("\t ")); assertNull(NeoInserter.clean("\u0000")); assertNull(NeoInserter.clean("\u0001")); assertNull(NeoInserter.clean("\u0002")); assertEquals("Abies", NeoInserter.clean("Abies")); assertEquals("öAbies", NeoInserter.clean("öAbies")); assertEquals("Abies mille", NeoInserter.clean(" Abies mille")); assertEquals("Abies x", NeoInserter.clean("Abies\u0000x")); assertEquals("Abies x", NeoInserter.clean("Abies\u0000\u0000\u0000x")); assertEquals("Abies x", NeoInserter.clean("Abies\u0000\u0001x")); }