anchor.diff:  
   .Example:
   This configuration specifies an index size trigger that monitors collections "test1" and "test2",
  -with both bytes (1GB) and number of docs (1 mln) upper limits, and a custom `belowOp`
  +with both bytes (1GB) and number of docs (1 million) upper limits, and a custom `belowOp`
   operation `NONE` (which still can be monitored and acted upon by an appropriate trigger listener):
   
   [source,json]
  
positive.code: `aboveBytes`
  
  `aboveDocs`:: upper threshold expressed as the number of documents. This value is compared with `SEARCHER.searcher.numDocs` metric.
  Note: due to the way Lucene indexes work a shard may exceed the `aboveBytes` threshold
  even if the number of documents is relatively small, because replaced and deleted documents keep
  occupying disk space until they are actually removed during Lucene index merging.
  
  
negative.code: 
  Similarly, when either of the lower thresholds is exceeded the trigger will generate an
  event with a (configurable) requested operation to perform on two of the smallest
  shards. By default this is a MERGESHARDS operation, and is currently ignored because
  that operation is not yet implemented (see https://issues.apache.org/jira/browse/SOLR-9407[SOLR-9407]).
  
  Additionally, monitoring can be restricted to a list of collections; by default
  all collections are monitored.
  
  This trigger supports the following configuration parameters (all thresholds are exclusive):
  