private Runnable checkForMissingColocatedRegionRunnable() {
    return this::checkForMissingColocatedRegion;
  }
Updates the missing colocated child region list and returns a copy of the list.

<p>
The list of missing child regions is normally updated lazily, only when this logger thread
periodically wakes up to log warnings about the colocated regions that are still missing. This
method performs an on-demand update of the list so if called between logging intervals the
returned list is current.
geode-core/src/main/java/org/apache/geode/internal/cache/partitioned/colocation/SingleThreadColocationLogger.java