I've created a Dialect and a UniqueDelegate subcIass and I was able to suppress the ALTER TABLE statements by that.
However I couldn't get the unique(...) statement to be appended to the "CREATE TABLE ..." statements. So I looked at the 4.2.2 sources and
found a disabled line of code in UniqueKey.java. I think this is the reason why I can't manage to get the unique constraints on the CREATE TABLE.
Is my suspicion wrong?

@Override
public String sqlConstraintString(
Dialect dialect,
String constraintName,
String defaultCatalog,
String defaultSchema)

{ // return dialect.getUniqueDelegate().uniqueConstraintSql( this ); // Not used. return ""; }