driver-core/src/main/com/mongodb/client/model/Accumulators.java
public static <TExpression> BsonField max(final String fieldName, final TExpression expression) {
        return accumulator("$max", fieldName, expression);
    }
public static <TExpression> BsonField max(final String fieldName, final TExpression expression) {
        return accumulator("$max", fieldName, expression);
    }
Gets a field name for a $group operation representing the maximum 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/max/ $max