default OUT visit(IN input, StartpointOldest startpointOldest) {
    throw new UnsupportedOperationException("StartpointOldest is not supported.");
  }
Performs a sequence of operations using IN and {@link StartpointOldest} and returns the result of the execution.
@param input the input metadata about the startpoint.
@param startpointOldest the {@link Startpoint} that represents the earliest offset.
@return the result of executing the operations defined by the visit method.
samza-api/src/main/java/org/apache/samza/startpoint/StartpointVisitor.java