Collector - Don't Allow Null Values

[DanAllen]

I have an inspection complete yes/no domain field in my arcgis.com map.  Every point in the map was pre-populated with an attribute value of "No" before I published it to ArcGIS.com.  When the inspection is complete, the user changes the value from No to Yes and the symbol changes color on the map from red to green.

The problem is collector allows the user to input a <null> value, which is not symbolized for, so the point disappears from the map, since I have "other" turned off in the symbol settings. 

Is there a way to force Collector to only allow the Yes/No, and not accept the Null value?  Or do I have to go back to may source data and turn off null values, then republish my feature service?

Thanks

Dan

[DanAllen]

Also, I tried going to the rest service admin directory / Update layer definition -  for my feature service, and changing "nullable" : true, to "nullable" : false, for the yes/no field in question, but it doesn't seem to accept my change, and goes right back to "nullable" : true, after I save.

[DanAllen]

Also, the ArcGIS.com pop up edit window and web appbulider smart editor widget only shows me Yes/No values.  But if I go to the Collector app or the web appbuilder Batch Edit widget, I get the choice, Yes/No/No Value.