public static <TExpression> BsonField first(final String fieldName, final TExpression expression) {
        return accumulator("$first", fieldName, expression);
    }
public static <TExpression> BsonField first(final String fieldName, final TExpression expression) {
        return accumulator("$first", fieldName, expression);
    }
public static < TExpression > BsonField first ( final String fieldName , final TExpression expression ) { return accumulator ( "$first" , fieldName , expression ) ; }
Gets a field name for a $group operation representing the value of the given expression when applied to the first member 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/first/ $first
Gets a field name for a $group operation representing the value of the given expression when applied to the first member of the group .