fix warning

Author: breedx-splk

exporters/common/src/main/java/io/opentelemetry/exporter/internal/marshal/UnsafeAccess.java

@@ -71,7 +71,7 @@ static long getLong(Object o, long offset) {
   private UnsafeAccess() {}
 
   private static class UnsafeHolder {
-    public static final Unsafe UNSAFE;
+    private static final Unsafe UNSAFE;
 
     static {
       UNSAFE = getUnsafe();