int unionFieldCount = type.getSubtypesCount();
LazyTreeReader[] unionFields = new LazyTreeReader[unionFieldCount];
for(int i=0; i < unionFieldCount; ++i) {
unionFields[i] = createLazyTreeReader(type.getSubtypes(i), types, included);
}
return new LazyUnionTreeReader(columnId, rowIndexStride, unionFields);
default:
throw new IllegalArgumentException("Unsupported type " +
type.getKind());
}
}