Currently no way to get position of a primary key column in a primary key.
Reassigned to new owner.
From the API (org.netbeans.modules.db.metadata.model.api.PrimaryKey#getColumns):
"Get the list of columns for this primary key. The collection is ordered based on the sequencing of the primary key."
So a user could be bold enough to cast to java.util.List other ordered collections don't seem to be to fitting. Guarded with an instanceof and a fallback to "List<Column> columns = new ArrayList<>(pk.getColumns())" should do it.