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org.apache.kafka.streams.processor.ProcessorContext:

  * Headers headers();

org.apache.kafka.streams.processor.MockProcessorContext:

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  * setRecordMetadata(final String topic, final int partition, final long offset, final Headers headers, final long timestamp)   
...
  * ConsumerRecord<byte[], byte[]> create(final String topicName, final K key, final V value, final Headers headers, final long timestampMs)
  * ConsumerRecord<byte[], byte[]> create(final String topicName, final K key, final V value, final Headers headers)
  * ConsumerRecord<byte[], byte[]> create(final String topicName, final V value, final Headers headers, final long timestampMs)
  * ConsumerRecord<byte[], byte[]> create(final String topicName, final V value, final Headers headers)
  * ConsumerRecord<byte[], byte[]> create(final K key, final V value, final Headers headers, final long timestampMs)
  * ConsumerRecord<byte[], byte[]> create(final K key, final V value, final Headers headers)
  * ConsumerRecord<byte[], byte[]> create(final V value, final Headers headers, final long timestampMs)
  * ConsumerRecord<byte[], byte[]> create(final V value, final Headers headers)
Proposed Changes
Adding `headers()` to `ProcessorContext` will enable custom processors and future DSL processors to have Headers available.
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