code: public static <TExpression> BsonField min(final String fieldName, final TExpression expression) {
          return accumulator("$min", fieldName, expression);
      }
docs: Gets a field name for a $group operation representing the minimum of the values of the given expression when applied to all
  members of the group.
  
  @param fieldName the field name
  @param expression the expression
  @param <TExpression> the expression type
  @return the field
  @mongodb.driver.manual reference/operator/aggregation/min/ $min