Addressed code review comments to use getVersion() in forward index…

… reader to fetch version number.

pinot-segment-local/src/main/java/org/apache/pinot/segment/local/io/writer/impl/VarByteChunkForwardIndexWriterV4.java

@@ -107,15 +107,21 @@ public VarByteChunkForwardIndexWriterV4(File file, ChunkCompressionType compress
     writeHeader(_chunkCompressor.compressionType(), chunkSize);
   }
 
-  public int getVersion() {
+  // Child class must shadow this static method
+  public static int getVersion() {
+    return VERSION;
+  }
+
+  // Child class must override this class instance method
+  protected int getConcreteClassVersion() {
     return VERSION;
   }
 
   private void writeHeader(ChunkCompressionType compressionType, int targetDecompressedChunkSize)
       throws IOException {
     // keep metadata BE for backwards compatibility
     // (e.g. the version needs to be read by a factory which assumes BE)
-    _output.writeInt(getVersion());
+    _output.writeInt(getConcreteClassVersion());
     _output.writeInt(targetDecompressedChunkSize);
     _output.writeInt(compressionType.getValue());
     // reserve a slot to write the data offset into

pinot-segment-local/src/main/java/org/apache/pinot/segment/local/io/writer/impl/VarByteChunkForwardIndexWriterV5.java

@@ -73,12 +73,12 @@
  * <p>Note that the {@code VERSION} tag is a {@code static final} class variable set to {@code 5}. Since static
  * variables are shadowed in the child class thus associated with the class that defines them, care must be taken to
  * ensure that the parent class can correctly observe the child class's {@code VERSION} value at runtime. To handle
- * this cleanly and correctly, the {@code getVersion()} method is overridden to return the concrete subclass's
- * {@code VERSION} value, ensuring that the correct version number is returned even when using a reference
+ * this cleanly and correctly, the {@code getConcreteClassVersion()} method is overridden to return the concrete
+ * subclass's {@code VERSION} value, ensuring that the correct version number is returned even when using a reference
  * to the parent class.</p>
  *
  * @see VarByteChunkForwardIndexWriterV4
- * @see VarByteChunkForwardIndexWriterV5#getVersion()
+ * @see VarByteChunkForwardIndexWriterV5#getConcreteClassVersion()
  */
 @NotThreadSafe
 public class VarByteChunkForwardIndexWriterV5 extends VarByteChunkForwardIndexWriterV4 {
@@ -89,8 +89,14 @@ public VarByteChunkForwardIndexWriterV5(File file, ChunkCompressionType compress
     super(file, compressionType, chunkSize);
   }
 
+  // Hide the parent class getVersion()
+  public static int getVersion() {
+    return VERSION;
+  }
+
+  // Override the parent class getConcreteClassVersion();
   @Override
-  public int getVersion() {
+  public int getConcreteClassVersion() {
     return VERSION;
   }
 

pinot-segment-local/src/main/java/org/apache/pinot/segment/local/segment/index/readers/forward/VarByteChunkForwardIndexReaderV4.java

@@ -82,7 +82,8 @@ public VarByteChunkForwardIndexReaderV4(PinotDataBuffer dataBuffer, FieldSpec.Da
 
   public void validateIndexVersion(PinotDataBuffer dataBuffer) {
     int version = dataBuffer.getInt(0);
-    Preconditions.checkState(version == VarByteChunkForwardIndexWriterV4.VERSION, "Illegal index version: %s", version);
+    Preconditions.checkState(version == VarByteChunkForwardIndexWriterV4.getVersion(), "Illegal index version: %s",
+        version);
   }
 
   @Override

pinot-segment-local/src/main/java/org/apache/pinot/segment/local/segment/index/readers/forward/VarByteChunkForwardIndexReaderV5.java

@@ -40,7 +40,8 @@ public VarByteChunkForwardIndexReaderV5(PinotDataBuffer dataBuffer, FieldSpec.Da
   @Override
   public void validateIndexVersion(PinotDataBuffer dataBuffer) {
     int version = dataBuffer.getInt(0);
-    Preconditions.checkState(version == VarByteChunkForwardIndexWriterV5.VERSION, "Illegal index version: %s", version);
+    Preconditions.checkState(version == VarByteChunkForwardIndexWriterV5.getVersion(), "Illegal index version: %s",
+        version);
   }
 
   @Override