public void writeStartpoint(SystemStreamPartition ssp, TaskName taskName, Startpoint startpoint) {
    Preconditions.checkState(!stopped, "Underlying metadata store not available");
    Preconditions.checkNotNull(ssp, "SystemStreamPartition cannot be null");
    Preconditions.checkNotNull(startpoint, "Startpoint cannot be null");

    try {
      readWriteStore.put(toReadWriteStoreKey(ssp, taskName), objectMapper.writeValueAsBytes(startpoint));
      readWriteStore.flush();
    } catch (Exception ex) {
      throw new SamzaException(String.format(
          "Startpoint for SSP: %s and task: %s may not have been written to the metadata store.", ssp, taskName), ex);
    }
  }
Writes a {@link Startpoint} that defines the start position for a {@link SystemStreamPartition} and {@link TaskName}.
@param ssp The {@link SystemStreamPartition} to map the {@link Startpoint} against.
@param taskName The {@link TaskName} to map the {@link Startpoint} against.
@param startpoint Reference to a Startpoint object.
samza-core/src/main/java/org/apache/samza/startpoint/StartpointManager.java