code: public AggregateExplainOperation hint(final BsonValue hint) {
          isTrueArgument("BsonString or BsonDocument", hint == null || hint.isDocument() || hint.isString());
          this.hint = hint;
          return this;
      }
docs: Sets the hint for which index to use. A null value means no hint is set.
  
  @param hint the hint
  @return this
  @since 3.6
  @mongodb.server.release 3.6