### Question:
FileValidationUtils { public static boolean validFileNamePart(final String part) { return part == null || part.isEmpty() || !part.contains(File.separator); } private  FileValidationUtils(); static boolean validFileNamePart(final String part);  }### Answer:
@Test public void testValidFileNamePart() { assertThat(validFileNamePart("")).isTrue(); assertThat(validFileNamePart("Hello World!")).isTrue(); assertThat(validFileNamePart(File.separator)).isFalse(); assertThat(validFileNamePart("/foo\\")).isFalse(); }