The CREATE SCHEMA statement is subject to access control when running in sqlAuthorization mode.
Only the database owner can create a schema with name different from the current user name and
only the the database owner can specify AUTHORIZATION <user>, with a user name other than the
current user name, cf comment in StatementSchemaPermission#check, ca line 86.
These restrictions are not described in http://db.apache.org/derby/docs/dev/ref/rrefsqlj31580.html.