Fix misc. issues

Author: pawankartik-elastic

server/src/main/java/org/elasticsearch/action/fieldcaps/FieldCapabilitiesResponse.java

@@ -320,6 +320,7 @@ public static class Builder {
         private List<FieldCapabilitiesIndexResponse> indexResponses = Collections.emptyList();
         private List<FieldCapabilitiesFailure> failures = Collections.emptyList();
         private TransportVersion minTransportVersion = null;
+        private ResolvedIndexExpressions resolvedIndexExpressions = null;
 
         private Builder() {}
 
@@ -366,6 +367,11 @@ public Builder withMinTransportVersion(TransportVersion minTransportVersion) {
             return this;
         }
 
+        public Builder withResolvedIndexExpressions(ResolvedIndexExpressions resolvedIndexExpressions) {
+            this.resolvedIndexExpressions = resolvedIndexExpressions;
+            return this;
+        }
+
         public FieldCapabilitiesResponse build() {
             return new FieldCapabilitiesResponse(
                 indices,
@@ -375,7 +381,7 @@ public FieldCapabilitiesResponse build() {
                 indexResponses,
                 failures,
                 minTransportVersion,
-                null
+                resolvedIndexExpressions
             );
         }
     }

server/src/main/java/org/elasticsearch/action/fieldcaps/TransportFieldCapabilitiesAction.java

@@ -379,38 +379,43 @@ private <R extends ActionResponse> void doExecuteForked(
              * this, we use `CountDown` and track each response, irrespective of whether it's valid or not, and then perform the
              * reconciliation when it has counted down and the request is a resolvable CPS request.
              */
-            CountDown countDownResponses = new CountDown(remoteClusterIndices.size());
+            Runnable crossProjectReconciler;
             Map<String, ResolvedIndexExpressions> linkedProjectsResponses = ConcurrentCollections.newConcurrentMap();
-            Runnable crossProjectReconciler = () -> {
-                if (countDownResponses.countDown() && crossProjectEnabled) {
-                    /*
-                     * This happens when one or more linked projects respond with an error instead of a valid response -- say, networking
-                     * error.
-                     */
-                    if (linkedProjectsResponses.size() != remoteClusterIndices.size()) {
-                        listener.onFailure(
-                            new IllegalArgumentException(
-                                "Invalid number of responses received: "
-                                    + linkedProjectsResponses.size()
-                                    + " vs expected "
-                                    + remoteClusterIndices.size()
-                            )
-                        );
-                        return;
-                    }
+            if (remoteClusterIndices.size() > 0) {
+                CountDown countDownResponses = new CountDown(remoteClusterIndices.size());
+                crossProjectReconciler = () -> {
+                    if (countDownResponses.countDown() && crossProjectEnabled) {
+                        /*
+                         * This happens when one or more linked projects respond with an error instead of a valid response -- say
+                         * networking error.
+                         */
+                        if (linkedProjectsResponses.size() != remoteClusterIndices.size()) {
+                            listener.onFailure(
+                                new IllegalArgumentException(
+                                    "Invalid number of responses received: "
+                                        + linkedProjectsResponses.size()
+                                        + " vs expected "
+                                        + remoteClusterIndices.size()
+                                )
+                            );
+                            return;
+                        }
 
-                    Exception validationEx = CrossProjectIndexResolutionValidator.validate(
-                        request.indicesOptions(),
-                        null,
-                        request.getResolvedIndexExpressions(),
-                        linkedProjectsResponses
-                    );
+                        Exception validationEx = CrossProjectIndexResolutionValidator.validate(
+                            request.indicesOptions(),
+                            null,
+                            request.getResolvedIndexExpressions(),
+                            linkedProjectsResponses
+                        );
 
-                    if (validationEx != null) {
-                        listener.onFailure(validationEx);
+                        if (validationEx != null) {
+                            listener.onFailure(validationEx);
+                        }
                     }
-                }
-            };
+                };
+            } else {
+                crossProjectReconciler = () -> {};
+            }
 
             // this is the cross cluster part of this API - we force the other cluster to not merge the results but instead
             // send us back all individual index results.
@@ -631,6 +636,7 @@ private static void mergeIndexResponses(
                         .withResolvedRemotelyBuilder(resolvedRemotely)
                         .withMinTransportVersion(minTransportVersion.get())
                         .withFailures(failures)
+                        .withResolvedIndexExpressions(request.getResolvedIndexExpressions())
                         .build()
                 );
             }