Apply suggestion from @anjalshireesh

Co-authored-by: Shireesh Anjal <355479+anjalshireesh@users.noreply.github.com>

Author: balamurugana

api/src/main/java/io/minio/MinioAsyncClient.java

@@ -583,20 +583,13 @@ protected CompletableFuture<Integer> calculatePartCount(List<SourceObject> sourc
                   sources.set(index, source);
                 }
 
-                List<String> keys = new ArrayList<>();
+                List<String> keys = new ArrayList<>(Arrays.asList("source", source.bucket() + "/" + source.object()));
                 if (source.versionId() != null && !source.versionId().isEmpty()) {
                   keys.add("version_id=" + source.versionId());
                 }
                 if (source.offset() != null) keys.add("offset=" + source.offset());
                 if (source.length() != null) keys.add("length=" + source.length());
                 String sourceMessage = String.join(" ", keys);
-                sourceMessage =
-                    "source "
-                        + source.bucket()
-                        + "/"
-                        + source.object()
-                        + (sourceMessage.isEmpty() ? "" : " ")
-                        + sourceMessage;
                 if ((source.offset() != null ? source.offset() : 0) >= source.objectSize()) {
                   throw new IllegalArgumentException(
                       "source "