Remove redundant transformation

Signed-off-by: Rishab Nahata <[email protected]>

CHANGELOG.md

@@ -103,6 +103,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Compress and cache cluster state during validate join request ([#7321](https://github.com/opensearch-project/OpenSearch/pull/7321))
 - [Snapshot Interop] Add Changes in Create Snapshot Flow for remote store interoperability. ([#7118](https://github.com/opensearch-project/OpenSearch/pull/7118))
 - Add new query profile collector fields with concurrent search execution ([#7898](https://github.com/opensearch-project/OpenSearch/pull/7898))
+- Check UTF16 string size before converting to String to avoid OOME ([#7963](https://github.com/opensearch-project/OpenSearch/pull/7963))
 
 ### Deprecated
 

server/src/main/java/org/opensearch/common/bytes/AbstractBytesReference.java

@@ -85,13 +85,12 @@ public void writeTo(OutputStream os) throws IOException {
     @Override
     public String utf8ToString() {
         BytesRef bytesRef = toBytesRef();
-        char[] ref = new char[bytesRef.length];
-        int len = UnicodeUtil.UTF8toUTF16(bytesRef.bytes, bytesRef.offset, bytesRef.length, ref);
+        final char[] ref = new char[bytesRef.length];
+        final int len = UnicodeUtil.UTF8toUTF16(bytesRef.bytes, bytesRef.offset, bytesRef.length, ref);
         if (len > MAX_LENGTH) {
-            throw new IllegalStateException("UTF16 String size is " + len +
-                ", should be less than " + MAX_LENGTH);
+            throw new IllegalStateException("UTF16 String size is " + len + ", should be less than " + MAX_LENGTH);
         }
-        return bytesRef.utf8ToString();
+        return new String(ref, 0, len);
     }
 
     @Override