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public interface HoodieRecordPayload<T extends HoodieRecordPayload> extends Serializable {
 /**
   * When more than one HoodieRecord have the same HoodieKey, this function combines them before attempting to insert/upsert by taking in a property map.
   * Implementation can leverage the property to decide their business logic to do preCombine.
   * @param another instance of another {@link HoodieRecordPayload} to be combined with.
   * @param properties Payload related properties. For example pass the ordering field(s) name to extract from value in storage.
   * @return the combined value
   */
  default T preCombine(T another, Properties properties);

/**
   * This methods lets you write custom merging/combining logic to produce new values as a function of current value on storage and whats contained
   * in this object. Implementations can leverage properties if required.
   * <p>
   * eg:
   * 1) You are updating counters, you may want to add counts to currentValue and write back updated counts
   * 2) You may be reading DB redo logs, and merge them with current image for a database row on storage
   * </p>
   *
   * @param currentValue Current value in storage, to merge/combine this payload with
   * @param schema Schema used for record
   * @param properties Payload related properties. For example pass the ordering field(s) name to extract from value in storage. 
   * @return new combined/merged value to be written back to storage. EMPTY to skip writing this record.
   */
  default Option<IndexedRecord> combineAndGetUpdateValue(IndexedRecord currentValue, Schema schema, Properties properties) throws IOException;
  
/**
   * Generates an avro record out of the given HoodieRecordPayload, to be written out to storage. Called when writing a new value for the given
   * HoodieKey, wherein there is no existing record in storage to be combined against. (i.e insert) Return EMPTY to skip writing this record.
   * Implementations can leverage properties if required.
   * @param schema Schema used for record
   * @param properties Payload related properties. For example pass the ordering field(s) name to extract from value in storage.
   * @return the {@link IndexedRecord} to be inserted.
   */
  @PublicAPIMethod(maturity = ApiMaturityLevel.STABLE)
  default Option<IndexedRecord> getInsertValue(Schema schema, Properties properties) throws IOException;

/**
   * This method can be used to extract some metadata from HoodieRecordPayload. The metadata is passed to {@code WriteStatus.markSuccess()} and
   * {@code WriteStatus.markFailure()} in order to compute some aggregate metrics using the metadata in the context of a write success or failure.
   * @return the metadata in the form of Map<String, String> if any.
   */
  @PublicAPIMethod(maturity = ApiMaturityLevel.STABLE)
  default Option<Map<String, String>> getMetadata() {
    return Option.empty();
  }

}