http://incubator.apache.org/derby/manuals/develop/develop109.html shows how to call org.apache.derby.database.UserUtility.add, but Derby doesn't support static method calls. The text below should be removed from src/documentation/content/xdocs/manuals/develop/develop109.ihtml:
Note:
Derby provides a utility to make it easier to create and maintain the lists of read-only and full-access users. This utility is org.apache.derby.database.UserUtility. The following example shows how to use the utility to add a full access user:
CALL org.apache.derby.database.UserUtility.add("mary",
UserUtility.FULL_ACCESS_PERMISSION);