This commit changes the exception type thrown when trying to (#22921)

create a snapshot with a name that already exists in the repository.
Instead of throwing a SnapshotCreateException, which results in a
generic 500 status code, a duplicate snapshot name will throw a
InvalidSnapshotNameException, which will result in a 400 status code
(bad request).

Author: Ali Beyad

core/src/main/java/org/elasticsearch/repositories/blobstore/BlobStoreRepository.java

@@ -94,6 +94,7 @@
 import org.elasticsearch.repositories.RepositoryData;
 import org.elasticsearch.repositories.RepositoryException;
 import org.elasticsearch.repositories.RepositoryVerificationException;
+import org.elasticsearch.snapshots.InvalidSnapshotNameException;
 import org.elasticsearch.snapshots.SnapshotCreationException;
 import org.elasticsearch.snapshots.SnapshotException;
 import org.elasticsearch.snapshots.SnapshotId;
@@ -308,10 +309,10 @@ public void initializeSnapshot(SnapshotId snapshotId, List<IndexId> indices, Met
             // check if the snapshot name already exists in the repository
             final RepositoryData repositoryData = getRepositoryData();
             if (repositoryData.getAllSnapshotIds().stream().anyMatch(s -> s.getName().equals(snapshotName))) {
-                throw new SnapshotCreationException(metadata.name(), snapshotId, "snapshot with the same name already exists");
+                throw new InvalidSnapshotNameException(metadata.name(), snapshotId.getName(), "snapshot with the same name already exists");
             }
             if (snapshotFormat.exists(snapshotsBlobContainer, snapshotId.getUUID())) {
-                throw new SnapshotCreationException(metadata.name(), snapshotId, "snapshot with such name already exists");
+                throw new InvalidSnapshotNameException(metadata.name(), snapshotId.getName(), "snapshot with the same name already exists");
             }
 
             // Write Global MetaData

core/src/test/java/org/elasticsearch/snapshots/SharedClusterSnapshotRestoreIT.java

@@ -25,7 +25,6 @@
 import org.elasticsearch.action.ListenableActionFuture;
 import org.elasticsearch.action.admin.cluster.repositories.put.PutRepositoryResponse;
 import org.elasticsearch.action.admin.cluster.snapshots.create.CreateSnapshotResponse;
-import org.elasticsearch.action.admin.cluster.snapshots.delete.DeleteSnapshotResponse;
 import org.elasticsearch.action.admin.cluster.snapshots.get.GetSnapshotsResponse;
 import org.elasticsearch.action.admin.cluster.snapshots.restore.RestoreSnapshotResponse;
 import org.elasticsearch.action.admin.cluster.snapshots.status.SnapshotIndexShardStage;
@@ -2450,7 +2449,7 @@ public void testCannotCreateSnapshotsWithSameName() throws Exception {
                                            .get();
             fail("should not be allowed to create a snapshot with the same name as an already existing snapshot: " +
                  createSnapshotResponse.getSnapshotInfo().snapshotId());
-        } catch (SnapshotCreationException e) {
+        } catch (InvalidSnapshotNameException e) {
             assertThat(e.getMessage(), containsString("snapshot with the same name already exists"));
         }