c# - Issue with JSON serialization in Unity -

i'm trying serialize array of custom monobehaviours, using json. know can't done directly, i'm using wrapper class , serializing instead.

this wrapper object

[system.serializable]  
public class wavescollection {
    public wave[] waves;
}

that's object being wrapped (only important bits of it)

[system.serializable]
public class wave : monobehaviour {
    [serializefield]public float[] appeartimes;//at time should n-th enemy appear;
    [serializefield]public vector2[] positions;//where should n-th enemy appear;
    [serializefield]public enemytype[] enemiestoappear;//what enemies should appear
}

        wavesarray = new wave[] {thiswave, thiswave, thiswave};
        wavescollection collection = new wavescollection();
        collection.waves = new wave[10];
        wavesarray.copyto(collection.waves, 0);
        streamwriter sw = file.createtext(writepath);
        string json = jsonutility.tojson(collection);
        sw.writeline(json);
        sw.close();

and that's code serializing. i've got array of non-null wave objects , copy wrapper object. try write in file , output is

{"waves":[{"instanceid":-99992},{"instanceid":-99992},{"instanceid":-99992},{"instanceid":0},{"instanceid":0},{"instanceid":0},{"instanceid":0},{"instanceid":0},{"instanceid":0},{"instanceid":0}]}

could give me few directions on i'm doing wrong?