public <T> T unwrap(Class<T> clazz) {
if (clazz.isInstance(this)) {
return clazz.cast(this);
}
if (clazz.isInstance(OptiqSchema.this)) {
return clazz.cast(OptiqSchema.this);
}
if (clazz.isInstance(OptiqSchema.this.schema)) {
return clazz.cast(OptiqSchema.this.schema);
}
throw new ClassCastException("not a " + clazz);
}
