### Question:
NestedMetadata { static void putHeaderAttributes(Map<String, String> attributes, ObjectNode metadata) { putAttributes(attributes, metadata, HEADER, ""); } private  NestedMetadata(); static byte[] mergedPayload(byte[] payload, byte[] metadata); static ObjectNode attributesToMetadataPayload(Map<String, String> attributes); static void stripPayloadMetadataToAttributes(Map<String, String> attributes,
      ObjectNode payload);  }### Answer:
@Test public void testPutHeaderAttributes() throws Exception { ObjectNode metadata = mapToObjectNode(ImmutableMap.of("header", ImmutableMap.of("dnt", "1", "x_debug_id", "mysession", "x_source_tags", "automation, perf"))); Map<String, String> expected = ImmutableMap.of("dnt", "1", "x_debug_id", "mysession", "x_source_tags", "automation, perf"); Map<String, String> attributes = new HashMap<>(); NestedMetadata.putHeaderAttributes(attributes, (metadata)); assertEquals(expected, attributes); }