public static Optional<InputStream> getInputStreamFromFileNameAndClassLoader(String fileName, ClassLoader classLoader) {
        return Optional.ofNullable(classLoader.getResourceAsStream(fileName));
    }
@Test
    public void getInputStreamFromFileNameNotExisting() {
        Optional<InputStream> retrieved = FileUtils.getInputStreamFromFileNameAndClassLoader(NOT_EXISTING_FILE, FileUtilsTest.class.getClassLoader());
        assertThat(retrieved).isNotPresent();
    }