[SalesForce] How to create this JSON structure using inner classes

I am trying to create a JSON payload in a VF controller to send to middleware. I tried to use JSONGenerator.writeStringField(String, String) but kept getting error: "Can not write a field name, expecting a value"

I found the following question and answer, so I decided to give up on writeStringField and try JSON.serialize on inner classes instead.
Writing JSON using JSONGenerator with writeStringField()

Here is an example of the structure (XML) that I need to mimic/create:

<SalesPersons>
    <SalesPerson>
        <RecordType/>
        <SalesPersonID>531</SalesPersonID>
        <Status>A</Status>
    </SalesPerson>
    <SalesPerson>
        <RecordType/>
        <SalesPersonID>538</SalesPersonID>
        <Status>A</Status>
    </SalesPerson>
</SalesPersons>

Here are the classes I created:

public class SalesPersons{
    List<SalesPerson> SalesPersons = new List<SalesPerson>();
    public SalesPersons(){}

    public void addSalesPerson(SalesPerson sp){
        this.SalesPersons.add(sp);
    }
}
public class SalesPerson{
    String SalesPersonID;
    String SalesPersonType;
    String SubType;
    String SalesPersonName;

    public SalesPerson(User u){
        SalesPersonID = u.EmployeeNumber;
        SalesPersonType = 'S';
        SubType = 'P';
        SalesPersonName = u.Name;
    }
}

Here is the JSON Payload that gets created from this:

{
  "SalesPersons": [
    {
      "SubType": "P",
      "SalesPersonType": "S",
      "SalesPersonName": "SSO User",
      "SalesPersonID": "101"
    },
    {
      "SubType": "P",
      "SalesPersonType": "S",
      "SalesPersonName": "Admin User",
      "SalesPersonID": null
    }
  ]
}

Where I am stuck is on creating multiple arrays 'named' SalesPerson. The JSON that I am currently generating contains the info for multiple SalesPerson objects, but I need the String "SalesPerson" to be present in each.

Best Answer

A quick hack of the http://json2apex.herokuapp.com/ output produces:

// You can call the outer and inner classes whatever you like: its the
// field names and types that matter
public class SalesPersons {

    public class SalesPerson {
        public String SubType;
        public String SalesPersonType;
        public String SalesPersonName;
        public String SalesPersonID;
    }

    public SalesPerson[] SalesPersons = new SalesPerson[] {};

    public static SalesPersons parse(String jsonString) {
        return (SalesPersons) JSON.parse(jsonString, SalesPersons.class);
    }

    public String serializePretty() {
        return JSON.serializePretty(this);
    }

    public void addSalesPerson(User u) {
        SalesPerson sp = new SalesPerson();
        sp.SalesPersonID = u.EmployeeNumber;
        sp.SalesPersonType = 'S';
        sp.SubType = 'P';
        sp.SalesPersonName = u.Name;
        SalesPersons.add(sp);
    }
}

Note that lists and arrays are interchangeable in this context.

To build the JSON:

SalesPersons sps = new SalesPersons();
for (User u : [select Name, EmployeeNumber from User limit 1000]) {
    sps.addSalesPersons(u);
}

String jsonString = sps.serializePretty();
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