fix compilation error - set vectors to null

Author: narangvivek10

java/cuvs-java/src/main/java22/com/nvidia/cuvs/internal/CagraIndexImpl.java

@@ -145,6 +145,7 @@ private CagraIndexImpl(InputStream inputStream, CuVSResourcesImpl resources) thr
    * @param resources The resources instance
    */
   private CagraIndexImpl(IndexReference indexReference, CuVSResourcesImpl resources) {
+    this.vectors = null;
     this.cagraIndexParameters = null;
     this.cagraCompressionParams = null;
     this.dataset = null;