I noticed that Apache SOAP always serializes NULLs with xsi:null="true", the problem is that for the 2001 schema version there is no null attribute it got renamed to nil.
The quick fix is to change the definition of ATTR_NULL in constants.java, however it looks like the code supports both 1999 and 2001 schema, so really it needs to pick the correct attribute name based on the schema version in use. This will be a significant interop issue for people using nulls between Apache and non-Apache toolkits. Cheers Simon www.pocketsoap.com
