public FieldDescription getField(CompoundName globalName) {
        FieldDescription field = getField(globalName.first());
        if (field == null) return null;

        if (globalName.size() == 1) return field;

        FieldType fieldType = field.getType();
        if ( ! (fieldType instanceof QueryProfileFieldType)) return null;

        return ((QueryProfileFieldType)fieldType).getQueryProfileType().getField(globalName.rest());
    }
Returns the description of the given name under this, of null if none
container-search/src/main/java/com/yahoo/search/query/profile/types/QueryProfileType.java