Fix lint issues (#2527)

Author: andy-hf-kwok

common/src/main/scala/org/apache/spark/sql/comet/util/Utils.scala

@@ -223,9 +223,9 @@ object Utils extends CometTypeShim {
       writer.close()
 
       if (out.size() > 0) {
-        (batch.numRows(), cbbos.toChunkedByteBuffer)
+        (batch.numRows().toLong, cbbos.toChunkedByteBuffer)
       } else {
-        (batch.numRows(), new ChunkedByteBuffer(Array.empty[ByteBuffer]))
+        (batch.numRows().toLong, new ChunkedByteBuffer(Array.empty[ByteBuffer]))
       }
     }
   }

common/src/main/spark-3.x/org/apache/comet/shims/CometTypeShim.scala

@@ -20,6 +20,9 @@ package org.apache.comet.shims
 
 import org.apache.spark.sql.types.DataType
 
+import scala.annotation.nowarn
+
 trait CometTypeShim {
+    @nowarn // Spark 4 feature; stubbed to false in Spark 3.x for compatibility.
     def isStringCollationType(dt: DataType): Boolean = false
 }