### Question:
CachingPartitionerSerializerDelegate extends KinesisPartitioner<T> implements KinesisSerializationSchema<T> { @Override public String getExplicitHashKey(T element) { return getLastOrCreateNewSerializedRecord(element).getExplicitHashKey(); } CachingPartitionerSerializerDelegate(KinesisEgressSerializer<T> delegate); @Override ByteBuffer serialize(T element); @Override String getTargetStream(T element); @Override String getPartitionId(T element); @Override String getExplicitHashKey(T element);  }### Answer:
@Test public void explicitHashKey() { final CachingPartitionerSerializerDelegate<String> cachingDelegate = new CachingPartitionerSerializerDelegate<>(new DuplicateSerializationDetectingSerializer()); assertThat(cachingDelegate.getExplicitHashKey(TEST_INPUT), is(TEST_EXPLICIT_HASH_KEY)); }