Add toString() to MultiSearchRequest class.

fix #12144

Signed-off-by: Guillaume Alvarez <7364145+guillaume-alvarez@users.noreply.github.com>

Author: guillaume-alvarez

CHANGELOG.md

@@ -86,6 +86,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fix typo in API annotation check message ([11836](https://github.com/opensearch-project/OpenSearch/pull/11836))
 - Update supported version for must_exist parameter in update aliases API ([#11872](https://github.com/opensearch-project/OpenSearch/pull/11872))
 - [Bug] Check phase name before SearchRequestOperationsListener onPhaseStart ([#12035](https://github.com/opensearch-project/OpenSearch/pull/12035))
+- As toString methods to MultiSearchRequest, MultiGetRequest and CreateIndexRequest ([#12163](https://github.com/opensearch-project/OpenSearch/pull/12163))
 
 ### Security
 

server/src/main/java/org/opensearch/action/admin/indices/create/CreateIndexRequest.java

@@ -594,4 +594,25 @@ public void writeTo(StreamOutput out) throws IOException {
         }
         waitForActiveShards.writeTo(out);
     }
+
+    @Override
+    public String toString() {
+        return "CreateIndexRequest{"
+            + "cause='"
+            + cause
+            + '\''
+            + ", index='"
+            + index
+            + '\''
+            + ", settings="
+            + settings
+            + ", mappings='"
+            + mappings
+            + '\''
+            + ", aliases="
+            + aliases
+            + ", waitForActiveShards="
+            + waitForActiveShards
+            + '}';
+    }
 }

server/src/main/java/org/opensearch/action/get/MultiGetRequest.java

@@ -583,4 +583,19 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
         return builder;
     }
 
+    @Override
+    public String toString() {
+        return "MultiGetRequest{"
+            + "preference='"
+            + preference
+            + '\''
+            + ", realtime="
+            + realtime
+            + ", refresh="
+            + refresh
+            + ", items="
+            + items
+            + '}';
+    }
+
 }

server/src/main/java/org/opensearch/action/search/MultiSearchRequest.java

@@ -398,4 +398,16 @@ public boolean shouldCancelChildrenOnCancellation() {
             }
         };
     }
+
+    @Override
+    public String toString() {
+        return "MultiSearchRequest{"
+            + "maxConcurrentSearchRequests="
+            + maxConcurrentSearchRequests
+            + ", requests="
+            + requests
+            + ", indicesOptions="
+            + indicesOptions
+            + '}';
+    }
 }