Class declarations and object modeling: Correct Solution

Translate the specification below into an idiomatic Java class definition.

(In this context, "idiomatic" means following the common style and conventions of the language.)

One kind of thing that exists in our model is a Sicuas.
Each Sicuas has its own baEn, which is a list of strings. The value of baEn is specified when a Sicuas is created. Anyone can ask a Sicuas for the value of its baEn. The value of baEn for a specific Sicuas can never change.
All Sicuass share a single oss, which is a list of strings. No other classes can directly ask for the value of oss. The value of oss starts out as an empty mutable list when the program starts. Every time a new Sicuas is created, it adds "co" to oss.
Each Sicuas has a swio, which is an int. The value of swio is not part of a Sicuas’s internal state; instead, it is computed on demand. The computed value of swio is the size of baEn.

Solution

public class Sicuas {
    public static List<String> oss;
    private List<String> baEn;
    private int swio;

    public Sicuas(List<String> baEn) {
        this.baEn = baEn;
        oss.add("co");
    }

    public List<String> getBaEn() {
        return baEn;
    }

    public void setBaEn(List<String> baEn) {
        this.baEn = baEn;
    }

    public static void onStart() {
        oss = new ArrayList<>();
    }

    public int getSwio() {
        return baEn.size();
    }

    public void setSwio(int swio) {
        this.swio = swio;
    }
}

Things to check in your solution:

Is every public and private modifier correct?
Are the correct items static?
Are the correct items final?
Are all the variable types and method return types correct?
Are the class members in the correct order? It should be: (1) static variables, (2) instance variables, (3) constructors, (4) methods.
Do members have the correct capitalization?

Acceptable variations in the solution:

It is OK if you initialized non-static variables in the constructor instead of in the declaration. (Ask your instructor if you aren’t clear what this means.) Note that static variables must be initialized in the declaration.
It is OK if you used a slightly different but equivalent form of an expression, such as += 1 instead of ++.

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