Address review comments

Author: alexey-ivanov-es

server/src/main/java/org/elasticsearch/cluster/metadata/IndexNameExpressionResolver.java

@@ -479,26 +479,13 @@ private static void ensureRemoteExpressionRequireIgnoreUnavailable(IndicesOption
             return;
         }
         if (RemoteClusterAware.isRemoteIndexName(current)) {
-            List<String> crossClusterIndices = getRemoteIndexExpressions(expressions);
+            List<String> crossClusterIndices = RemoteClusterAware.getRemoteIndexExpressions(expressions);
             throw new IllegalArgumentException(
                 "Cross-cluster calls are not supported in this context but remote indices were requested: " + crossClusterIndices
             );
         }
     }
 
-    /**
-     * Extracts the list of remote index expressions from the given array of index expressions
-     */
-    public static List<String> getRemoteIndexExpressions(String... expressions) {
-        List<String> crossClusterIndices = new ArrayList<>();
-        for (int i = 0; i < expressions.length; i++) {
-            if (RemoteClusterAware.isRemoteIndexName(expressions[i])) {
-                crossClusterIndices.add(expressions[i]);
-            }
-        }
-        return crossClusterIndices;
-    }
-
     /**
      * Translates the provided index expression into actual concrete indices, properly deduplicated.
      *

server/src/main/java/org/elasticsearch/transport/RemoteClusterAware.java

@@ -69,6 +69,19 @@ public static boolean isRemoteIndexName(String indexExpression) {
         return idx > 0 && isSelector == false;
     }
 
+    /**
+     * Extracts the list of remote index expressions from the given array of index expressions
+     */
+    public static List<String> getRemoteIndexExpressions(String... expressions) {
+        List<String> crossClusterIndices = new ArrayList<>();
+        for (int i = 0; i < expressions.length; i++) {
+            if (isRemoteIndexName(expressions[i])) {
+                crossClusterIndices.add(expressions[i]);
+            }
+        }
+        return crossClusterIndices;
+    }
+
     /**
      * @param indexExpression expects a single index expression at a time (not a csv list of expression)
      * @return cluster alias in the index expression. If none is present, returns RemoteClusterAware.LOCAL_CLUSTER_GROUP_KEY

server/src/test/java/org/elasticsearch/cluster/metadata/IndexNameExpressionResolverTests.java

@@ -78,7 +78,6 @@
 import static org.hamcrest.Matchers.emptyArray;
 import static org.hamcrest.Matchers.endsWith;
 import static org.hamcrest.Matchers.equalTo;
-import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.notNullValue;
 import static org.hamcrest.Matchers.nullValue;
@@ -3487,23 +3486,6 @@ public void testResolveWriteIndexAbstractionMultipleMatches() {
         );
     }
 
-    public void testGetRemoteIndexExpressions() {
-        {
-            List<String> remoteIndexExpressions = IndexNameExpressionResolver.getRemoteIndexExpressions("index-1");
-            assertThat(remoteIndexExpressions, empty());
-        }
-        {
-            List<String> remoteIndexExpressions = IndexNameExpressionResolver.getRemoteIndexExpressions(
-                "index-1",
-                "remote:index-1",
-                "idx-*",
-                "remote-2:idx-5"
-            );
-            assertThat(remoteIndexExpressions, hasSize(2));
-            assertThat(remoteIndexExpressions, contains("remote:index-1", "remote-2:idx-5"));
-        }
-    }
-
     public static IndexMetadata.Builder indexBuilder(String index) {
         return indexBuilder(index, Settings.EMPTY);
     }

server/src/test/java/org/elasticsearch/transport/RemoteClusterAwareTests.java

@@ -16,10 +16,13 @@
 import java.util.Map;
 import java.util.Set;
 
+import static org.hamcrest.Matchers.contains;
 import static org.hamcrest.Matchers.containsInAnyOrder;
 import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.empty;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.hasKey;
+import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.not;
 
 public class RemoteClusterAwareTests extends ESTestCase {
@@ -158,6 +161,23 @@ public void testGroupClusterIndicesFail() {
 
     }
 
+    public void testGetRemoteIndexExpressions() {
+        {
+            List<String> remoteIndexExpressions = RemoteClusterAware.getRemoteIndexExpressions("index-1");
+            assertThat(remoteIndexExpressions, empty());
+        }
+        {
+            List<String> remoteIndexExpressions = RemoteClusterAware.getRemoteIndexExpressions(
+                "index-1",
+                "remote:index-1",
+                "idx-*",
+                "remote-2:idx-5"
+            );
+            assertThat(remoteIndexExpressions, hasSize(2));
+            assertThat(remoteIndexExpressions, contains("remote:index-1", "remote-2:idx-5"));
+        }
+    }
+
     private static class RemoteClusterAwareTest extends RemoteClusterAware {
         RemoteClusterAwareTest() {
             super(Settings.EMPTY);