public String getTaskName() {
    return getKey();
  }
The change log mapping message is used to store changelog partition information for a given task name.
@param source Source writing the change log mapping
@param taskName The task name to be used in the mapping
@param changelogPartitionNumber The partition to which the task's changelog is mapped to
samza-core/src/main/java/org/apache/samza/coordinator/stream/messages/SetChangelogMapping.java