MultipartBody { public String getValueAsString(String key) { if ((_values != null) && _values.containsKey(key)) { return _values.get(key); } return null; } private  MultipartBody(
		Map<String, BinaryFile> binaryFiles,
		ObjectMapperProvider objectMapperProvider, Map<String, String> values); static MultipartBody of(
		Map<String, BinaryFile> binaryFiles,
		ObjectMapperProvider objectMapperProvider, Map<String, String> values); BinaryFile getBinaryFile(String key); byte[] getBinaryFileAsBytes(String key); T getValueAsInstance(String key, Class<T> clazz); Optional<T> getValueAsInstanceOptional(
			String key, Class<T> clazz); String getValueAsString(String key); Map<String, String> getValues();  }
@Test public void testGetValueAsString() { MultipartBody multipartBody = MultipartBody.of( Collections.emptyMap(), __ -> _objectMapper, Collections.singletonMap("key", "value")); assertThat(multipartBody.getValueAsString("key"), is("value")); assertThat(multipartBody.getValueAsString("null"), is(nullValue())); }