In all existing versions of Jaybird it is not possible to execute CREATE DATABASE using a JDBC statement. This will yield a "java.sql.SQLSyntaxErrorException: Dynamic SQL Error; SQL error code = -530; Cannot prepare a CREATE DATABASE/SCHEMA statement [SQLState:42000, ISC error code:335544597]". However dropping to the low-level API to try and use executeImmediate will simply do nothing. And connecting but not attach allows to create a database using a native connection, but not using a pure-java connection.
We need to investigate whether it is possible to execute CREATE DATABASE when attached to a database, and if so: how.
See also https://github.com/FirebirdSQL/jaybird/issues/27