[#2353] Improvement: Fix the warning: unchecked method invocation: method sendCachedBuffer in class RMRecordsReader.RecordsCombiner is applied to given types (#2358)

### What changes were proposed in this pull request?
Fix the warning: unchecked method invocation: method `sendCachedBuffer` in class `RMRecordsReader.RecordsCombiner` is applied to given types

### Why are the changes needed?
Fix: #2353

### Does this PR introduce _any_ user-facing change?
No.

### How was this patch tested?
current UT

<img width="1114" alt="image" src="https://github.com/user-attachments/assets/1ac86c0d-d902-47e0-8ff9-1de3fbc3299c" />

Author: cchung100m

client/src/main/java/org/apache/uniffle/client/record/reader/RMRecordsReader.java

@@ -448,7 +448,7 @@ class RecordsFetcher extends Thread {
     RecordsFetcher(int partitionId) {
       this.partitionId = partitionId;
       this.sleepTime = initFetchSleepTime;
-      this.recordBuffer = new RecordBuffer(partitionId);
+      this.recordBuffer = new RecordBuffer<>(partitionId);
       this.nextQueue =
           combiner == null ? mergeBuffers.get(partitionId) : combineBuffers.get(partitionId);
       this.serverInfos = shuffleServerInfoMap.get(partitionId);
@@ -512,7 +512,7 @@ public void run() {
               // split into two different threads, then will be asynchronous processes. Although it
               // seems to save time, it actually consumes more memory.
               reader =
-                  new RecordsReader(
+                  new RecordsReader<>(
                       rssConf,
                       SerInputStream.newInputStream(byteBuf),
                       keyClass,
@@ -526,7 +526,7 @@ public void run() {
                 }
                 if (recordBuffer.size() >= maxRecordsNumPerBuffer) {
                   nextQueue.put(recordBuffer);
-                  recordBuffer = new RecordBuffer(partitionId);
+                  recordBuffer = new RecordBuffer<>(partitionId);
                 }
                 recordBuffer.addRecord(reader.getCurrentKey(), reader.getCurrentValue());
               }
@@ -561,12 +561,12 @@ class RecordsCombiner extends Thread {
     // The RecordBuffer has a capacity limit, records for the same key may be
     // distributed in different RecordBuffers. So we need a cachedBuffer used
     // to record the buffer of the last combine.
-    private RecordBuffer cached;
+    private RecordBuffer<K, C> cached;
     private Queue<RecordBuffer> nextQueue;
 
     RecordsCombiner(int partitionId) {
       this.partitionId = partitionId;
-      this.cached = new RecordBuffer(partitionId);
+      this.cached = new RecordBuffer<>(partitionId);
       this.nextQueue = mergeBuffers.get(partitionId);
       setName("RecordsCombiner-" + partitionId);
     }
@@ -589,13 +589,13 @@ public void run() {
             //   we can send the cached to downstream directly.
             if (cached.size() > 0 && !isSameKey(cached.getLastKey(), current.getFirstKey())) {
               sendCachedBuffer(cached);
-              cached = new RecordBuffer(partitionId);
+              cached = new RecordBuffer<>(partitionId);
             }
 
             // 3 combine the current, then cache it. By this way, we can handle the specical case
             // that next record
             // buffer has same key in current.
-            RecordBlob recordBlob = new RecordBlob(partitionId);
+            RecordBlob recordBlob = new RecordBlob<>(partitionId);
             recordBlob.addRecords(current);
             recordBlob.combine(combiner, isMapCombine);
             for (Object record : recordBlob.getResult()) {
@@ -616,7 +616,7 @@ public void run() {
     private void sendCachedBuffer(RecordBuffer<K, C> cachedBuffer) throws InterruptedException {
       // Multiple records with the same key may span different recordbuffers. we were only combined
       // within the same recordbuffer. So before send to downstream, we should combine the cached.
-      RecordBlob recordBlob = new RecordBlob(partitionId);
+      RecordBlob recordBlob = new RecordBlob<K, C, Object>(partitionId);
       recordBlob.addRecords(cachedBuffer);
       recordBlob.combine(combiner, true);
       RecordBuffer recordBuffer = new RecordBuffer<>(partitionId);