src/main/java/com/conveyal/gtfs/loader/JdbcTableWriter.java
private static Set<Table> getReferencingTables(Table table) {
        Set<Table> referencingTables = new HashSet<>();
        for (Table gtfsTable : Table.tablesInOrder) {
            // IMPORTANT: Skip the table for the entity we're modifying or if loop table does not have field.
            if (table.name.equals(gtfsTable.name)) continue;
            for (Field field : gtfsTable.fields) {
                if (field.isForeignReference() && field.referenceTable.name.equals(table.name)) {
                    // If any of the table's fields are foreign references to the specified table, add to the return set.
                    referencingTables.add(gtfsTable);
                }
            }
        }
        return referencingTables;
    }
private static Set<Table> getReferencingTables(Table table) {
        Set<Table> referencingTables = new HashSet<>();
        for (Table gtfsTable : Table.tablesInOrder) {
            // IMPORTANT: Skip the table for the entity we're modifying or if loop table does not have field.
            if (table.name.equals(gtfsTable.name)) continue;
            for (Field field : gtfsTable.fields) {
                if (field.isForeignReference() && field.referenceTable.name.equals(table.name)) {
                    // If any of the table's fields are foreign references to the specified table, add to the return set.
                    referencingTables.add(gtfsTable);
                }
            }
        }
        return referencingTables;
    }
Finds the set of tables that reference the parent entity being updated.