I want to avoid overriding static fields.  In general, static fields that may be needed by subclasses should be accessed through accessor methods which may be overridden by subclasses. 

In this particular case, the static should be named FEATUREMAP_JS_NAME and specify just the resource name, not the path (i.e. featureList.js) and AbstractHttpTransport.getFeatureListResourceUri() should return getComboUri() + FEATUREMAP_JS_NAME