add stopIndex in Stoptime

application/src/main/java/org/opentripplanner/apis/gtfs/datafetchers/StoptimeImpl.java

@@ -85,6 +85,11 @@ public DataFetcher<Integer> scheduledDeparture() {
     return environment -> missingValueToNull(getSource(environment).getScheduledDeparture());
   }
 
+  @Override
+  public DataFetcher<Integer> stopIndex() {
+    return environment -> getSource(environment).getStopIndex();
+  }
+
   @Override
   public DataFetcher<Integer> stopPosition() {
     return environment -> getSource(environment).getGtfsSequence();

application/src/main/java/org/opentripplanner/apis/gtfs/generated/GraphQLDataFetchers.java

@@ -1093,6 +1093,8 @@ public interface GraphQLStoptime {
 
     public DataFetcher<Object> stop();
 
+    public DataFetcher<Integer> stopIndex();
+
     public DataFetcher<Integer> stopPosition();
 
     public DataFetcher<Boolean> timepoint();

application/src/main/java/org/opentripplanner/apis/gtfs/generated/GraphQLTypes.java

@@ -1,6 +1,7 @@
 // THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
 package org.opentripplanner.apis.gtfs.generated;
 
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;

application/src/main/resources/org/opentripplanner/apis/gtfs/schema.graphqls

@@ -2195,6 +2195,14 @@ type Stoptime {
   "The stop where this arrival/departure happens"
   stop: Stop
   """
+  The index of the stop in the pattern. This is required to start from 0 and be consecutive.
+  
+  The purpose of this field is to identify the position of the stop within the pattern so it can be
+  cross-referenced between different trips on the same pattern, as stopPosition can be different
+  between trips even within the same pattern.
+  """
+  stopIndex: Int!
+  """
   The sequence of the stop in the pattern. This is not required to start from 0 or be consecutive - any
   increasing integer sequence along the stops is valid.