mergeAction 
  Specifies a merge action. Valid values: simple, custom. If simple, merge behavior is defined by MergeWhenMatched and MergeWhenNotMatched. If custom, defined by MergeClause.
Specifies a merge action. Valid values: simple, custom. If simple, merge behavior is defined by MergeWhenMatched and MergeWhenNotMatched. If custom, defined by MergeClause.