anchor.diff:  ++++
   
   Returns cluster nodes statistics.
  -
   
   [[cluster-nodes-stats-api-request]]
   ==== {api-request-title}
  
positive.code: 
  [[cluster-nodes-stats-api-response-body-os]]
  ===== `os` section
  
  The `os` flag can be set to retrieve statistics that concern
  the operating system:
  
  `os.timestamp`::
      Last time the operating system statistics have been refreshed.
  
negative.code:     (integer)
      Number of failed operations for the processor.
  
  [[cluster-nodes-stats-api-response-body-adaptive-selection]]
  ===== `adaptive_selection` section
  
  The `adaptive_selection` statistics are keyed by node. For each node:
  
  `adaptive_selection.outgoing_searches`::
      The number of outstanding search requests from the node these stats are for 
  