A couple of improvements for the Catalog API:

Null handling consistency:
As specified for the package, passing a null argument to a constructor or method in any class or interface will cause a NullPointerException to be thrown. But there was an exception in CatalogManager's methods that took null as default feature setting.

Incorrect reference to java.io.Reader:
The CatalogUriResolver resolve method stated that if no mapping is found, returns a javax.xml.transform.Source object containing an empty java.io.Reader if the javax.xml.catalog.resolve property is set to ignore. This is incorrect because Source does not have a reference to Reader.