diff --git a/server/src/main/java/org/elasticsearch/action/fieldcaps/FieldCapabilitiesResponse.java b/server/src/main/java/org/elasticsearch/action/fieldcaps/FieldCapabilitiesResponse.java
index 15dd44d97d058..e3fcd5bbd200d 100644
--- a/server/src/main/java/org/elasticsearch/action/fieldcaps/FieldCapabilitiesResponse.java
+++ b/server/src/main/java/org/elasticsearch/action/fieldcaps/FieldCapabilitiesResponse.java
@@ -36,20 +36,20 @@ public class FieldCapabilitiesResponse extends ActionResponse implements Chunked
     public static final ParseField FAILURES_FIELD = new ParseField("failures");
 
     private final String[] indices;
-    private final Map<String, Map<String, FieldCapabilities>> responseMap;
+    private final Map<String, Map<String, FieldCapabilities>> fields;
     private final List<FieldCapabilitiesFailure> failures;
     private final List<FieldCapabilitiesIndexResponse> indexResponses;
 
     public FieldCapabilitiesResponse(
         String[] indices,
-        Map<String, Map<String, FieldCapabilities>> responseMap,
+        Map<String, Map<String, FieldCapabilities>> fields,
         List<FieldCapabilitiesFailure> failures
     ) {
-        this(indices, responseMap, Collections.emptyList(), failures);
+        this(indices, fields, Collections.emptyList(), failures);
     }
 
-    public FieldCapabilitiesResponse(String[] indices, Map<String, Map<String, FieldCapabilities>> responseMap) {
-        this(indices, responseMap, Collections.emptyList(), Collections.emptyList());
+    public FieldCapabilitiesResponse(String[] indices, Map<String, Map<String, FieldCapabilities>> fields) {
+        this(indices, fields, Collections.emptyList(), Collections.emptyList());
     }
 
     public FieldCapabilitiesResponse(List<FieldCapabilitiesIndexResponse> indexResponses, List<FieldCapabilitiesFailure> failures) {
@@ -58,19 +58,19 @@ public FieldCapabilitiesResponse(List<FieldCapabilitiesIndexResponse> indexRespo
 
     private FieldCapabilitiesResponse(
         String[] indices,
-        Map<String, Map<String, FieldCapabilities>> responseMap,
+        Map<String, Map<String, FieldCapabilities>> fields,
         List<FieldCapabilitiesIndexResponse> indexResponses,
         List<FieldCapabilitiesFailure> failures
     ) {
-        this.responseMap = Objects.requireNonNull(responseMap);
+        this.fields = Objects.requireNonNull(fields);
         this.indexResponses = Objects.requireNonNull(indexResponses);
         this.indices = indices;
         this.failures = failures;
     }
 
     public FieldCapabilitiesResponse(StreamInput in) throws IOException {
-        indices = in.readStringArray();
-        this.responseMap = in.readMap(FieldCapabilitiesResponse::readField);
+        this.indices = in.readStringArray();
+        this.fields = in.readMap(FieldCapabilitiesResponse::readField);
         this.indexResponses = FieldCapabilitiesIndexResponse.readList(in);
         this.failures = in.readCollectionAsList(FieldCapabilitiesFailure::new);
     }
@@ -98,7 +98,7 @@ public int getFailedIndicesCount() {
      * Get the field capabilities map.
      */
     public Map<String, Map<String, FieldCapabilities>> get() {
-        return responseMap;
+        return fields;
     }
 
     /**
@@ -120,7 +120,7 @@ public List<FieldCapabilitiesIndexResponse> getIndexResponses() {
      * Get the field capabilities per type for the provided {@code field}.
      */
     public Map<String, FieldCapabilities> getField(String field) {
-        return responseMap.get(field);
+        return fields.get(field);
     }
 
     /**
@@ -141,7 +141,7 @@ private static Map<String, FieldCapabilities> readField(StreamInput in) throws I
     @Override
     public void writeTo(StreamOutput out) throws IOException {
         out.writeStringArray(indices);
-        out.writeMap(responseMap, FieldCapabilitiesResponse::writeField);
+        out.writeMap(fields, FieldCapabilitiesResponse::writeField);
         FieldCapabilitiesIndexResponse.writeList(out, indexResponses);
         out.writeCollection(failures);
     }
@@ -160,7 +160,7 @@ public Iterator<? extends ToXContent> toXContentChunked(ToXContent.Params params
             Iterators.single(
                 (b, p) -> b.startObject().array(INDICES_FIELD.getPreferredName(), indices).startObject(FIELDS_FIELD.getPreferredName())
             ),
-            Iterators.map(responseMap.entrySet().iterator(), r -> (b, p) -> b.xContentValuesMap(r.getKey(), r.getValue())),
+            Iterators.map(fields.entrySet().iterator(), r -> (b, p) -> b.xContentValuesMap(r.getKey(), r.getValue())),
             this.failures.size() > 0
                 ? Iterators.concat(
                     Iterators.single(
@@ -182,14 +182,14 @@ public boolean equals(Object o) {
         if (o == null || getClass() != o.getClass()) return false;
         FieldCapabilitiesResponse that = (FieldCapabilitiesResponse) o;
         return Arrays.equals(indices, that.indices)
-            && Objects.equals(responseMap, that.responseMap)
+            && Objects.equals(fields, that.fields)
             && Objects.equals(indexResponses, that.indexResponses)
             && Objects.equals(failures, that.failures);
     }
 
     @Override
     public int hashCode() {
-        int result = Objects.hash(responseMap, indexResponses, failures);
+        int result = Objects.hash(fields, indexResponses, failures);
         result = 31 * result + Arrays.hashCode(indices);
         return result;
     }
diff --git a/server/src/main/java/org/elasticsearch/action/fieldcaps/TransportFieldCapabilitiesAction.java b/server/src/main/java/org/elasticsearch/action/fieldcaps/TransportFieldCapabilitiesAction.java
index e9960c832953c..dde4b81af94d2 100644
--- a/server/src/main/java/org/elasticsearch/action/fieldcaps/TransportFieldCapabilitiesAction.java
+++ b/server/src/main/java/org/elasticsearch/action/fieldcaps/TransportFieldCapabilitiesAction.java
@@ -459,7 +459,7 @@ private static FieldCapabilitiesResponse merge(
         final FieldCapabilitiesIndexResponse[] indexResponses = indexResponsesMap.values().toArray(new FieldCapabilitiesIndexResponse[0]);
         Arrays.sort(indexResponses, Comparator.comparing(FieldCapabilitiesIndexResponse::getIndexName));
         final String[] indices = Arrays.stream(indexResponses).map(FieldCapabilitiesIndexResponse::getIndexName).toArray(String[]::new);
-        final Map<String, Map<String, FieldCapabilities.Builder>> responseMapBuilder = new HashMap<>();
+        final Map<String, Map<String, FieldCapabilities.Builder>> fieldsBuilder = new HashMap<>();
         int lastPendingIndex = 0;
         for (int i = 1; i <= indexResponses.length; i++) {
             if (i == indexResponses.length || hasSameMappingHash(indexResponses[lastPendingIndex], indexResponses[i]) == false) {
@@ -469,17 +469,17 @@ private static FieldCapabilitiesResponse merge(
                 } else {
                     subIndices = ArrayUtil.copyOfSubArray(indices, lastPendingIndex, i);
                 }
-                innerMerge(subIndices, responseMapBuilder, request, indexResponses[lastPendingIndex]);
+                innerMerge(subIndices, fieldsBuilder, request, indexResponses[lastPendingIndex]);
                 lastPendingIndex = i;
             }
         }
 
         task.ensureNotCancelled();
-        Map<String, Map<String, FieldCapabilities>> responseMap = Maps.newMapWithExpectedSize(responseMapBuilder.size());
+        Map<String, Map<String, FieldCapabilities>> fields = Maps.newMapWithExpectedSize(fieldsBuilder.size());
         if (request.includeUnmapped()) {
-            collectResponseMapIncludingUnmapped(indices, responseMapBuilder, responseMap);
+            collectFieldsIncludingUnmapped(indices, fieldsBuilder, fields);
         } else {
-            collectResponseMap(responseMapBuilder, responseMap);
+            collectFields(fieldsBuilder, fields);
         }
 
         // The merge method is only called on the primary coordinator for cross-cluster field caps, so we
@@ -493,7 +493,7 @@ private static FieldCapabilitiesResponse merge(
                 );
             }
         }
-        return new FieldCapabilitiesResponse(indices, Collections.unmodifiableMap(responseMap), failures);
+        return new FieldCapabilitiesResponse(indices, Collections.unmodifiableMap(fields), failures);
     }
 
     private static boolean shouldLogException(Exception e) {
@@ -506,13 +506,13 @@ private static boolean shouldLogException(Exception e) {
             && ExceptionsHelper.isNodeOrShardUnavailableTypeException(e) == false;
     }
 
-    private static void collectResponseMapIncludingUnmapped(
+    private static void collectFieldsIncludingUnmapped(
         String[] indices,
-        Map<String, Map<String, FieldCapabilities.Builder>> responseMapBuilder,
-        Map<String, Map<String, FieldCapabilities>> responseMap
+        Map<String, Map<String, FieldCapabilities.Builder>> fieldsBuilder,
+        Map<String, Map<String, FieldCapabilities>> fieldsMap
     ) {
         final Set<String> mappedScratch = new HashSet<>();
-        for (Map.Entry<String, Map<String, FieldCapabilities.Builder>> entry : responseMapBuilder.entrySet()) {
+        for (Map.Entry<String, Map<String, FieldCapabilities.Builder>> entry : fieldsBuilder.entrySet()) {
             var typeMapBuilder = entry.getValue().entrySet();
 
             // do this directly, rather than using the builder, to save creating a whole lot of objects we don't need
@@ -527,17 +527,17 @@ private static void collectResponseMapIncludingUnmapped(
             if (unmapped != null) {
                 res.put("unmapped", unmapped.apply(resSize > 1));
             }
-            responseMap.put(entry.getKey(), Collections.unmodifiableMap(res));
+            fieldsMap.put(entry.getKey(), Collections.unmodifiableMap(res));
         }
     }
 
-    private static void collectResponseMap(
-        Map<String, Map<String, FieldCapabilities.Builder>> responseMapBuilder,
-        Map<String, Map<String, FieldCapabilities>> responseMap
+    private static void collectFields(
+        Map<String, Map<String, FieldCapabilities.Builder>> fieldsBuilder,
+        Map<String, Map<String, FieldCapabilities>> fields
     ) {
-        for (Map.Entry<String, Map<String, FieldCapabilities.Builder>> entry : responseMapBuilder.entrySet()) {
+        for (Map.Entry<String, Map<String, FieldCapabilities.Builder>> entry : fieldsBuilder.entrySet()) {
             var typeMapBuilder = entry.getValue().entrySet();
-            responseMap.put(entry.getKey(), Collections.unmodifiableMap(capabilities(typeMapBuilder.size(), typeMapBuilder)));
+            fields.put(entry.getKey(), Collections.unmodifiableMap(capabilities(typeMapBuilder.size(), typeMapBuilder)));
         }
     }